imperialscum said:
They consider themselves as an "experts" of film and are presenting their subjective opinions as something objective.
I know it's anecdotal, but Roger Ebert -- as a film critic -- doesn't match this description at all.
He was famously modest and managed to evaluate every movie he viewed in the context of what its director was trying to achieve; e.g., http://www.rogerebert.com/reviews/the-delta-force-1986.