Overevaluating owner vs. Car pimps.

Who is worse to deal with, the OVEREVALUATING owner, who does not really want to sell, or the car pimps who wanted the car for 5k, only to sell it on kijiji for 10k ?

When dealing with someone on a personal basis I find it difficult to put a price on another man's stuff. That said, when dealing with someone that is in it for a buck, I have no problem lowballing. I guess I would rather deal with a personal sale over a flipper.