What do you think of a guy that lies about his age?

Yeah it is annoying and makes them un-dateable. Hmm trying to think of why a guy would lie. I think in some cases he really does think of himself as young at heart, I mean a guy who is say 35 actually is pretty much mentally the same as 25 in most respects. Most 35-40yo guys would be entirely happy to go out out with women who are about 21-30 . Although most women who are say 21 or 22 want to go out with a guy who is also about the same age.