Ethically, if you find something of great value at a garage sale, should you inform the seller or quietly pay and take the item?

Nope.
Caveat Lector, translates to let the reader beware. I’m not sure the what that has to do with this thread.
Caveat Venditor, is pseudo legalese for let the seller beware, but it doesn’t mean that the seller needs to beware of the “real value” of the item for sale. It applies to the concept of real and implicit warranties. It requires the seller to “be aware” of what the buyer can rightly assume the product is warranted to provide. Which means that if I sell a product that a buyer rightly assume will provide some sort of ability or service then I as the seller must be aware, legally of that assumption. For instance, if I sell an aftermarket auto part (let’s say, a sun shade for a 2007 Pontiac Grand Prix) then that part must meet or exceed a reasonable expectation on the buyer’s part as to quality and reliability and compatibility. In other words: it’s reasonable for a buyer to expect that that sun shade fit in the windshield of the specified car and, you know, actually block the sun. And if it doesn’t, then I, the seller must be aware, the the buyer will expect satisfaction in the form of a replacement that does do those things or a refund.

As for the case you “cited:” there are plenty of reasons why a judge would uphold the sale. A judge’s jurisdiction in such a case revolves around whether there is a valid contract or not. If the buyer did not misrepresent themselves or the “true value” of the object, or cause, in some way, for that value to be hidden from the seller, then the the judge could determine there was no fraud involved and therefore the contract, and sale, were valid.

But, the op didn’t ask if the sale was legal, they asked if it was ethical. There’s often a lot of real estate between what is legal and what is ethical.

Further proof, if proof were needed, that my Latin stinks.

No argument there.

I don’t think there’s anything unethical about paying the asking price for something, even if it’s dramatically below the market price. There’s no coercion or trickery, no fraud, no false representations. Buyers don’t make representations about what they’re buying.

Knowledge has value, and in some specific circumstances it can have a lot of value. You’re not obligated to give some random person the benefit of your art history education any more than you’re obligated to do other knowledge work for free.

This question reminds me of the parable of the mechanic who is called in to fix a major problem with a complicated machine. He examines it for a while, then takes out a small hammer, gives a few taps in specific places, and the machine starts up. He provides his bill of $10,000, and the machine owner says “that’s ridiculous, you hardly did anything!”. And the mechanic’s response is that the payment is for the many years of experience that allowed him to fix it so quickly.

Sometimes knowing just where to tap is worth $10,000, and sometimes knowing just what a Ming bowl looks like is worth $700,000. Hundreds of people must have seen that bowl over the years and not one of them knew it’s worth. The guy who realized isn’t any more obligated to share the benefit of his expertise than the mechanic is obligated to fix the machine for $50 because it only took him a few minutes to do.

One of my friends loves to tell the story about when she cleaned out a deceased relative’s house, and their belongings included a set of three ceramic bud vases in different sizes that she thought were butt-ugly and she was going to discard them, but not after showing them to some other friends to laugh about their ugliness. One of them apparently recognized the artist’s name, which was on the bottom, and thought they might be worth something if they were authentic.

My friend took them to an antique dealer, who appraised the set at about $4,000 and offered her a few hundred in cash, which she happily took. Seriously, she said these things looked like they were one level above a kid’s craft project in art class.

I volunteer at the library, and we occasionally get valuable books and other items donated. If the librarians don’t wait them for the collection, we may sell it on Amazon, or take it to an auctioneer who will handle this for us. We had one book that we didn’t think was worth all that much - a couple hundred, maybe - but somebody out there was willing to pay $4,000 (there’s that number again!) for it.

Was it the version with the treasure map on the back?

So where is the line between “theft” and “great deal”?

Or what about a hypothetical scenario where something is a “great deal”, but maybe only to me because of my particular skills and connections? Like if I buy someone’s piece of junk car for $500, knowing that for a couple of grand I can restore it to a classic worth tens of thousands or more? But for most other people, it’s barely worth scrap.

I would congratulate you on your industriousness if that were my car you had purchased.

Cool story bro!
But you left out the part where the company agreed to the fee ahead of time. The fee was to fix the machine not for the knowledge. If the mechanic had taken weeks to fix the machine, it still would’ve cost $10k. Does it take any more or less knowledge of how the machine works to fix it with the tap of a hammer or weeks of hard work? Depends more in the job than on the knowledge.

As long as we’re playing fast and loose with the op’s scenario; try this one on. If your selling your property and you don’t know that it’s sitting on top of $50million worth or crude oil, but Exxon does is it ethical for them to give you your $100k asking price?

It seems from the rest of your post that you know exactly where the line is.

I think if Exxon put an offer on my property, I might suspect it is worth more than $100k.

You have to play “fast as loose” with the op’s scenario because there are simply too many potential variations.

I mean what if I sell you an old painting for $50, which you buy in good faith. A year later, you go to resell and find out a Jackson Pollock worth millions is hidden underneath. Do you owe me anything ethically? Do I need to hunt down whoever I bought it from and offer them something?

People at garage sales are often hot, tired, harried, and just want to get rid of the stuff. Take it out to the curb later if it doesn’t sell. If it was worth a fortune (a long-lost DaVinci) and I sold it for $1 million, I would if possible track the seller down and mail them an anonymous token amount of money, in cash. With a note saying an item they put out for sale was worth a lot and I wanted to share part of the money. … does this sound ok? too convoluted? unsafe? unethical? (actually I would put the money in a greeting card envelope and put it in their mailbox, yes, I know, the mailbox is nothing to treat that way, etc.)

I hardly ever go to garage sales. I do sometimes like to go to charity and thrift shops. Many items there are not properly priced from my perspective. Much crap is greatly overpriced. Sometimes very expensive clothing or other items
are sold for peanuts - but this is not the scenario being discussed, and the “profits” would be in the hundreds of dollars in the unlikely event of finding a buyer.

I know it is worth millions? And not a reproduction or parody or fake? I’m not that smart. But I’d buy it. I might well give a portion of the sale to the person or shop if they were unjerkish or the cause was good. I might not always feel obliged to do so - might depend on the details.

Which reminded me of this movie.

On a related note, a couple years ago, I was at an estate sale, and I almost didn’t buy the $4 bag of sewing patterns, most of which were cut. I did anyway, and I sure was glad I did, because when I inspected them, one at a time, before listing them on my Amazon account, I found a grand total of $82 in cash stowed away in them, in crisp bills printed in 1984. Because they didn’t look like current bills, cashiers wondered if they were real!

Had I found the money while I was there, I would have given that money to the people running the sale, but I didn’t, so it was mine.

If it’s undervalued but the difference is small, it’s worth $10 and she wants $5, I might assume a desire to just move it quickly, or just a difference in what she or I think it’s worth.

But large differences where a non-commercial seller clearly doesn’t understand the worth? No. There’s no point where I’ll take it and run.

I think I agree with this.

A pawn is shop is owned by a person. What’s the difference?

Because the whole point of their business is that they are supposed to know what things are worth. If they don’t then they are poor business people.

That said, I went to Vegas and took some men’s rings with me to pawn at the Pawn Stars Gold and Silver pawnshop store. Didn’t meet with any of the “stars” but sold three rings to the guy working at the time and accepted his offer. Then he told me that he was going to give ~$200-$300 more than that because he said that he didn’t have enough good men’s rings to sell and that they were a hot item in his shop because people from out of town always go there and want to but something to remember the place by. Seems that men who win at the gambling table like to buy rings with part of their winnings to show they are a Vegas big shot and buying them there makes for part of a good story.

They sometimes do that on the show as well and I was impressed by their integrity. It also makes for good word of mouth advertising.

I’m still not clear on what sort of item one could be talking about, here, that a garage-sale customer could recognize as worth millions, before the deal is made. I mean, I can imagine that maybe, just maybe, someone has a Picasso and doesn’t realize it, and sells it at a garage sale. And if a trained and experienced art critic recognizes it and buys it for $2, then what they’ll have is a pretty piece of painted canvas that they can hang above their sofa, which is exactly what the previous owner thought they were selling. They’re not going to be able to turn around and sell it to an art collector for millions, without a heck of a lot of documentation to prove that it’s actually a Picasso. And getting that documentation is going to require the cooperation of the previous owner, and they can charge whatever they want for that cooperation, now with the knowledge of what they’re dealing with.

Probably not very feasible, but imagine if some object appears to be just that, a big heavy object, but in fact contains an immense amount of gold in it (like maybe a cabinet that had a hidden drawer that the owner didn’t know about, with valuables stashed within)

Will anything like that ever happen again unlikely but sometimes I eyeball old frames wondering about it!

We have a big old rental house goes back to 1875 and it just sold so the garage has to be emptied of junk. There’s an old upright piano that came from some saloon that’s gotta go but now I want to poke about its insides in case of idk silver dollar tips, baseball cards, a treasure hoard!?

I think it’s most reasonable to suppose the seller chose the price through lack of awareness, similarly to how one might forget one’s wallet on a countertop at some store. It’s essentially a mistake. The only ethical choice is to point out this mistake, rather than taking personal advantage of it by quietly running off with the wallet or sale item. If after this the seller leaves the item for sale at that price, buying it is fine, like keeping an intentionally discarded wallet.