Do you give the members of your forum rep or do you let other members handle that? Do you treat people with - rep any different from people + rep people? How do you manage the reputation system on your forum?
I let the members handle the rep system. I give out positive rep to the people I that I think deserve it. I only gave out negative rep once to a dude who rep'd someone down for supporting pornography in the Mature Discussion debate on it. Another time it was to a banned member because he signed up again and got banned again (predictably).
I don't allow negative rep on my forums, only positive. Giving -rep just seems like a way for people to "get back" at each other and generally causes others to feel differently if they receive -rep from somebody else.
People also use -rep just because of difference in opinion... which I feel is abuse of the rep system.
With only positive rep, you can either:
1)+rep for good posts
2)no rep for the other posts
3)if it a post is bad enough for -rep anyway, use the report system.