Do you believe that there are genuinely evil people on here?
Why, of course I do. Me, first and foremost. Were my innermost self somehow revealed, with all the patheticness and sordidness, with all the depraved thoughts that are so ugly in their smallness they would put to shame nearly anyone, in short, taking into consideration my distance from the one that is Good, I am evil and wicked and surely
"through me, the entire world is guilty", to paraphrase Fyodor Mikhailovich.
As one of my gurus had said

And I don't suspect others of being much better.
But my anthropo-scepticism notwithstanding, whether oriented towards myself or anyone else, to answer your question in a less flippant way, I have absolutely no idea whether there are or not.
I mean, I think I can speak for
Perun and for
Magnus, whom I genuinely believe not to be evil in the way you meant... but as for the others, I don't even know them, let alone vouching for the state of their soul. I mean, half of the accounts might be just some malfunctioning AI bots (I suspect
Azas the most of this
), some can have ulterior motives and
Mosh, seemingly the calmest, most decent and most well-rounded of the people here, might be spending his evenings methodically cutting up whores in his bathroom for all I know.
So take that statement as a hyperbole. The discussion here gets often rather heated, possibly a bit
too much for everyone to truly believe the other party is also "good" or at least trying to aim that way. Your own original post felt like really dripping with scorn so that you would seem to consider those to whom it was addressed almost necessarily either stupid or evil... and you can't possibly think yourself just the smartest.
In short
