We've had our share of liars, fantasists, trolls and just plain nutters.
I think the moderators stamp on them early now as they are rarer and rarer. We learn to ignore them.
And the simple fact is; who but an idiot is going to judge what someone says based purely on their claimed background:
'So after you were thrown out of NASA for being too clever and the spetznaz for being too tough, you decided to come here and give advice? Now you assure me I don't need a compass in the hills? Thanks I'll pass on that one.'
I recently got banned from Massad Ayoobs blog after asking him to produce some evidence for his absurd distortions of reality. Even other regular people on the blog pointed out I never said the things he claimed he was banning me for.
(Always a mistake to meet ones heroes).
Guess as people say it's down to us having good moderators without an axe to grind.

qjs