Why do some members stiff me?

I always treat people with honesty and respect.I have not bought anything from anyone on FABO but I sold a couple parts.I believe what comes around goes around.There are always a few bad apples in the bunch.And if some here screws me over I have a real good memory when it comes to that.But it seems for the most part theres alot of good people here.I know its hard to trust people anymore. Jim