How about having some annual membership awards, that are voted on by the community?
Most helpful poster
Most thoughtful poster
Most entertaining poster
the list goes on.
Then the winners could have something in their avatar or signature, showing their award.
IMHO - By dangling different awards, such as you listed, it can actully create the wrong atmosphere on a forum.
Members would be influenced to post answers or comments, for other motives, rather than just trying to be helpful.
I would think that the large majority of members here, just want to find simple, honest, helpful ...... answers, opinions, or directions.
I just don't feel that this is the kind of forum (community) that warrants awards, or award symbols, such as suggested.
I see your point, however if they are voted on yearly by the community, then wouldn't that weed out some of the posters you suggest might crop up? Your probably right though, it would take just one rotten apple to spoil the whole barrel.