Fence sitting !!

What is it with fence sitters thats irks me so much ? Maybe the fact that, they dont orient themselves with a common purpose or a with a team to do something constructive, and just want to do the talking(most of it negative)...that they cant see the work making any positive difference to the environment...or better still, dont see the work making a worthwhile impact on them.
Are such species always like this? Or have life experiences made them such....hesitant, doubtful n cynical? Maybe they will remain so all their life...or maybe their priorities lie somewhere else. Fence sitters (with a different set of priorities) is tolerable but what about pseudo-fencesitters(coined it on the fly) who pose as one with the sole intention of disrupting n stalling any assignment.