It's the internet. You're always going to get the odd person who childishly uses the spam rating in some kind of vendetta, or spams everything they disagree with. In my experience though these users are very much in the minority and it would be a shame to completely overhaul the whole ratings system - something I think adds value to the site - because a small minority are abusing it.
Would it possible to put a built-in cap on the amount of negative reps one is allowed to give out - like 3 a day or less? That would stop the culprits being able to go on neg repping binges - or at least slow them down. It would also encourage them to use the rating more carefully - I mean they might not want to use up all their precious spam ratings in one go in case they find something (or someone) else they want to spam later.
Would it possible to put a built-in cap on the amount of negative reps one is allowed to give out - like 3 a day or less? That would stop the culprits being able to go on neg repping binges - or at least slow them down. It would also encourage them to use the rating more carefully - I mean they might not want to use up all their precious spam ratings in one go in case they find something (or someone) else they want to spam later.