This is a blog about a bartender who takes away fake IDs, and is really good at identifying them:
http://rachelhyman.blogspot.com/I originally found it by a link on Slashdot, but that's not as important. It's just cool to read!
She talks about how, if somebody is caught buying alcohol underage, even if they have a fake ID, she is likely to lose her job, and her co-workers and boss will end up in court. And that's true, from what I know from being in that industry -- it's a big danger.