I would ask for pics and maybe even say “the fork angle looks a little odd in your ad pics; has the bike been crashed?” If the answer is no he will certainly say so, and if it’s yes he will have been alerted to the fact that he won’t be slipping it past you and will likely admit the truth. At least that’s my theory.

If it’s clean, that’s going to be a nice bike. Is it a DX-5000?