Whiny, low life 0bama advocates complained about being called trolls, so I invented S.P. for Site Pest.
From the Wiki:
“A pest is an animal which is detrimental to humans or human concerns. It is a loosely defined term, often overlapping with the related terms weeds, vermin, parasites, and pathogens.”
Traitor is likely the most appropriate word.
Since most site pests seem to have crap ($&*^)for brains, seeing them post makes me think of that old expression-as welcome at the party as a t—d in the punchbowl.
http://www.youtube.com/watch?v=hjG-ZA9L-L0