My wife will throw away anything she sees that is after its sell-by date. I will use things that are many, many months expired, depending on the product.
Today I needed some thermally-conductive epoxy. I bought this box surplus, and use it every now and again. I keep it in the refrigerator, and it still works fine:
Salt.
Are you married to my sister?? I can’t imagine how much food she’s wasted over the years.
Food gets the sniff test - if it passes, it gets used. Or if it’s getting green and fuzzy, it gets tossed.
Other stuff - I can’t off the top of my head think of anything. If it works, I’ll use it. If not, it’s garbage.
My over the counter cold medicines and Tylenol etc. Are at least a decade past. Some of my salad dressings go over a year past. I recently finished off my last jar of plum jelly that I made in the early 1980’s. Taste was good but color had turned brown.
If something does not actually expire, then it can be stored indefinitely and I do not think it can ever count as an “expired product”.
I’ve eaten salad dressing made by a company closed down for a decade. Expired has no meaning with salad dressing. I’ve eaten leftovers my gf deemed inappropriate for giving to the dogs.
My only problem with them is the oil starts to taste rancid after some length of time. If it smells or tastes rancid, I’ll toss it, but otherwise I’m fine with it.
I have a box of Kosher Salt in my pantry that I only use occasionally. I’ve had it for a while; I think over 30 years. It’s a big box and it’s almost empty. When I finish it and buy a new box, it will last me for the rest of my life.
LOL I am the same. When my relatives come over to visit they always check the expiration dates if I give them something to eat or drink lol.
I recently tossed a few soup cans from 2012/2015. 
It has an "expiration date, " so it counts by the OP’s initial definition. Which is just the title of the thread, but I elect to interpret it my way. So there. 
I’ve eaten 15 year old MREs that were stored properly.
Well, we have some Himalayan pink sea salt that has expired, but I think it will be good for the next million years or so. So, they put an use by date on it, so it counts.
So ground meat or chicken- toss. Bacon or ham- smell test.
On the subject of the OP, I’m not familiar with that kind of thermal epoxy, but regular five-minute epoxy definitely goes bad after a couple of years or so. “Bad” meaning that it takes a really long time to set, may not set at all, and won’t be very strong.
With regard to food, I’m relatively unconcerned about frozen stuff unless it’s been in the freezer for years, in which case the quality will probably have deteriorated badly so I’ll throw it out. The other day I made some frozen dim sum dumplings that had expired last November, 10 months ago. They were perfectly fine.
Conversely, I had some nice seasoned roast potatoes that had been in the fridge around three weeks. They looked and smelled just fine, and I was going to use them, but doing a bit of Googling the refrigerated shelf life was quoted as either 3 to 5 days or 5 to 7 days, depending on the type. So they went into the garbage. Who knows, they might have been OK, but that was just too long past the recommended keep time.
I’m a big fan of a particular type of organic romaine-iceberg lettuce hybrid. Its best-by date is usually less than week. I don’t worry about it. I keep it in a cold part of the fridge and if it’s still crisp and not discoloured or wilted, I’ll keep using it.
Oh god. Not the pink salt?!
That stuff can never leave. It just hangs around like your ne’er-do-well nephew.
Toss it. It’ll show back up for another meal.
I think it’s possessed by demons.
OTOH, I’ll use buttermilk til the container is empty. Hell, it comes spoiled.
What is the worse that can happen?
Yep, I dont see the attraction, myself.
I’ve a 30 year old block of cheddar, which I’ve had since about 2003. Its expiration date was 2004. I’m looking forward to cracking it open the next time all the kids and spouses join my wife and I.
Cheese and yogurt cultures; because they are live bacteria and fungi, they diminish in population over time, and are fairly worthless a year after their use-by date.
Antibiotics, I’m careful with. They can go weird and make you sick.
Most food I use other criteria (smells bad? slimy? tastes stale?)
Just yesterday I went to Epcot: I put sunscreen on, and I’m not quite sure that I’ve bought sunscreen since the plague began. I put spray sunscreen on my body, but the propellant had leaked out so what came out was vaguely yellow-colored liquid that nonetheless succeeded in preventing a burn once I rubbed it in. (I usually don’t rub in spray-on sunscreen even though the package tells you to, because the propellant causes even enough distribution for me. But this time it definitely only hit part of my limbs initially).
For my face, I used Neutrogena Baby Sunscreen, which is made out of only beeswax and titanium oxide. I’m pretty sure that it doesn’t go bad. I like it because I usually sweat when I need sunscreen and all other brands, even Neutrogena’s new regular sunscreen, will hurt my eyes when I sweat if I put it on my face.
At any rate, both sunscreens were several years old and still did the job.
you lucky dog.
I’ve thrown out salad dressing that smelled a little rancid. It does expire.
Probably the oldest stuff i have with an expiration date that i use is cough syrup. I recently found some old confirmed cough syrup from when i was a child. Next time i have an unproductive cough that prevents me from sleeping, I’ll use it, and not the newer stuff.
Umm…what is confirmed cough syrup?
Catholic?