Most simply, a playa hater is someone who openly criticizes, purposefully attempts to sabotage, or who indulges in any number of other activities/behaviors aimed at someone they consider a playa, or even at playas in general.
The derogatory aspect to the term comes in the idea that the person who's hatin
is really only jealous -- they playa hate because they wish they could be as successful, or alternately wishes they could somehow have the playa to themself.
So, of course, quite often a playa hater is someone who at some point or other feels they were done wrong by a playa.
"I was trying to talk to this girl, but she was hanging out with this dude who's a total playa hater. Everything I said, he tried to turn it around to make me an asshole..."