I hate those people!

I don't understand the people who are permanently in a bad mood.
I know that sometimes you have a bad day or something but there are some people who no matter what are pissed off and contribute to a bad atmosphere.
If that would be the case in my free time I would ignore them or not meet them.
But sometimes this people turn out to be your boss or colleague and you have to bare their presence on a daily basis.
In my opinion it doesn't take too much to put a smile on your face or at least act normal since we end up pretty often in stressful situations etc.Why make it worse, right? But I guess for this kind of people it is something normal.
I just hate them!
Anyway I take it more as challenge. Ah, I must have picked up this corporate language where shitty is being translated as challenge:)