I call BS. A casino is the **last **place one could get away with passing a counterfeit.
I was a bank teller a few years ago and fake bills just feel wrong - usually they are too smooth and/or slick. Even brand new crisp bills have a little bit of softness compared to other paper.
If you’ve never seen one, you’d probably never look. I got two $5 last year on a $10 lottery ticket from the 7-11, only one of them felt really soft. I figured it was just worn, but the cashier at the donair shop the next day said they wouldn’t take the bills w/o the silver stripes on them. I commented to my co-worker that I didn’t know they came w/o a stripe, at which time he clued me in.
I ended up spending it back at the same 7-11 the next week, so the balance of karma was retained. 
I just say it’s counterfeit, show them how I can tell, and give it back.
Joe
Most people don’t know this, but new-style bills are also coded by series. If it’s a 1996 hundred, the second letter of the serial will always be A, i.e. BA12345678E. In the next series released (1999), the second letter is always B, then in the 2001 series, C, etc. I caught one fake that was decently made, but was something like a 1996 hundred with the serial FN12345678Q - not possible.
Joe
Quoth KnitWit:
This is exactly why you should check for counterfeits if it’s a large enough bill that you’d be worried about losing it. Personally, whenever I get a $20 or higher, I always hold it up to the light and look for the watermark portrait.
Why would counterfeiters change serial numbers? Presumably they’re copying the rest of the text and graphics somewhere instead of recreating them, so why would the serial number ever be wrong?
If they were to make 200 copies and they all had the same number printed on them they’d probably have to go really far and wide to get rid of any of them instead of maybe being able to pass off two in one place then go a not too far distance and pass two of another at a different gas station or convenience store if the person behind the counter is even vaguely awake.
And an interesting link to info on North Korea’s alleged superdollars.
I’ll echo Oslo Ostragoth in calling BS on this guy’s story. In addition to a casino being unlikely to be fooled, modern printers and scanners (along with most professional imaging software) are designed specifically to reject currency images. Even with expensive equipment it would not be casual process; you’d have to be pretty dead-set on counterfeiting to take the time to circumvent the hardware filters.
Plus, I don’t think there’s any kind of paper you can just get at a place like Kinko’s, for any price, that feels even remotely close to the material used for U.S. currency. Probably a good reason for that. 
You’d think, right? I don’t have a good answer for that.
Joe
I hate to point this out (except that probably no one here has the equipment to imitate it), but the film To Live &Die in LA has an excellent scene in which Willem Dafoe’s character goes through the process of counterfeiting some bills.
It is, I believe, pretty accurate, and will show why a “high end printer” cannot do the job.
I doubt it’s a good test. I got several fake bills over the years, generally quite poorly made (yep… I didn’t pay attention) but none lacked the watermark. That’s just too obvious.
I’m yet to see (or at least notice) a counterfeited € bill, though.
Because someone might notice that they just recieved a bunch of bills with the same number on it?
I had a fake $10 bill one. I would have had no idea, except that I was in a club and it glowed under the blacklight.
Not that I don’t believe you, but, I’m going to have to try that with my scanner and printer.
Although, I’m pretty sure scanning and reproducing the detailed engravings on the bill will product a distinct moirepattern that will make the bills look fake.
I’ve known one person in my entire life who looked at serial numbers on currency. I bet there are a significant number of retail clerks who don’t even know bills have serial numbers, and an ultra-majority who don’t look at them. I’ve never paid for something and had the clerk go, WAIT . . . let me check that these two bills don’t have the same serial number!
At the gas station I used to work at, our 3rd shift guy took a fake $50. The manager showed it to everyone the next day. It was obviously printed on plain old printer paper, and it was bright neon green. And it was off-center.
We found some of these today in 100s.
They’re supposed to. Well, not the whole bill, but the security thread is specifically made to glow under a UV light, and in different colors for different denominations:
Make sure your scanner and banknote are both post 1996 design.
That might’ve not been fake… I’m not sure if this is true, but a bank teller I know once told me that like clothing that is laundered with some types of detergent it may glow under a black light (try pouring detergent right on clothing instead of mixing it in with the laundry wash, sometimes it will be black light active). If it was washed in the laundry with clothes close in a pocket under where detergent was put it might glow. I was once in a dance club and pulled out ones at the bar… I remember a couple glowed under the blacklight while others didn’t… I doubt anyone’s out there printing up ones.
Really? What was the tipoff that they’re fake? I always assumed from the official remarks about them that they’re practically impossible to tell apart from the real deal.