I was the admin of a forum a few years back and we ran into a similar conundrum. Folks on the boards wanted a rating system or "like" system for actual posts. We deemed the idea pretty much useless on the grounds that it was not helpful and spurred competition. Reddit uses "karma points" for posts and comments and folks sometimes will post useless stuff just to get points and others will brag about their amount of karma points. On the basis of "like" buttons, we found we would rather folks comment constructive advice or praise then to just click like. A like wasn't helpful in that environment, a comment about how good their stuff was or what might need some work was much more useful.
Sorry to hear folks are abusing the system here.