A couple of points: "It's a joke, you must have no sense of humor" is a lame

[Johonny]

32. humor much like sexism is a continuum

it is very hard to know where the line is drawn as some comedic acts are of course set to be intentionally mean spirit, and the comedic foil not likable. In general people are more willing to accept it if it is surround by a greater context like say Archie Bunker, but other times the comedic character is unlikable and their is no context. Andy Kaufman created several such characters. I won't pretend to tell comedians where to draw their line as many have reached success with unlikable characters, although I think it is safe to say those that do this will and do draw scorn. If the comedian can not take the heat then they should not perform their act. That said I think you will find most successful comedians are generally aware that not every bit they do will be accepted by every audience member because once again people's sense of humor is a continuum.