A joke is always made at someone or something's expense. I try to stay with making fun of ideas because humor that targets people is just disrespect in an ironic container.
I've seen, heard, and read a lot of humor that not only doesn't entertain me, it puts me off the humorist. It's like, okay, this guy's getting laughs for his stand-up routine, but what is he doing besides ranting and talking about people in an insulting way? That's not funny; that's just being an unpleasant person. That brand of behavior can be good if it's delivered right - i.e. a grumpy old man who is knowingly a bit feeble-minded and irrational can be entertaining. Some plainclothes punk criticizing everything without style or character is just obnoxious.
Being aware of this, I often worry about coming off that way. I use humor as an outlet for frustration, and if I distill it and refine it enough, it seems to come across the way I intended. But I'm not always sure of myself, and sometimes I'll flippantly throw something out there off the cuff and I seem to miss everyone's wavelength. Then I have to look back on what I wrote and I can't help but agree.
Then I feel like one of those funny people I don't like. It's a terrible feeling, but sometimes you score and sometimes you don't. Missing the target is how we improve our aim, but if your dart goes into someone's face, then you're in trouble.
Anyway - on to the next round.