1 He claims to be wealthy, yet never has any cash.
2 When negotiating a deal with you he asks for a discount.
3 He delays paying you, claiming to have cashflow problems.
4 He claims to be honest.
5 He gets nasty when confronted with the truth.
6 He has a "selective" recollection of events and agreements.
7 He is on trial, but claims that it is all a mistake.