And while a mid, I went to the BUD/S Indoc program, so I know enough about the SEALS to be able to catch the hordes of posers sitting at half the bars in Thailand (they all are either SEALS or SAS).
It's amazing how much of that you run into. Two of my best friends in college were SEALS, and through them I am on first name basis with probably 30 team guys, not to mention the integrated training exercises in San Diego etc.
The first thing I always ask is what class they were, to see if they know my buddies. Several time I have gotten a response like 95XX (since most training classes at A schools are numbered by year). To which the reply is "You are a f***ing fake, STFU." No SEAL is going to ever make a mistake on or forget his own class number. I saw my SEAL buddy (who is 6 foot 4, and running about 270 at the time) run that little Q&A once, to a really, REALLY funny result. A young lady did not think very much of her male companion at the end of that conversation. She was kept company though.
The legit guys most often won't even tell you that they are/were a SEAL. The longer it takes to get it out of them, the higher the probability is that it is true.