I have yet to see this mentioned, and I just thought of it. I don't know if anyone has ever played the game Fallout 2, but at one point you have a choice of becoming a Slaver. When you become a slaver, your character is detested by a lot of different people, especially the law. My idea for the bounty hunter's is that they would be disliked by the more lawless factions. To me this seems like it would circumvent the "why doesn't everyone just become a bounty hunter?" scenario.

I have never played Fallout 2, but that seems like a good idea. They need to make a way to resign from bounty hunter first though :)