Nine times out of ten a phony will claim to be special forces, those are the ones to question. There are often those that did serve that tend to embellish their time in the service. But they did serve. A few simple questions will tell a lot about someone's service. When were you there, what unit were you in? That sort of thing will tell a lot to the real vet. A little bit of basic information can be checked out easily with the internet.

The red flag is always those that claim to be special forces of some kind. But verifying service is not practical on here. won't work without invading privacy.