For me, effective, sustained humor requires the reader to identify with the subject. I would cite three reasons: 1) it allows you to laugh *with* them; 2) it allows you to anticipate the punchline, which is an important element of comedic timing; 3) it keeps your interest in longer works. I've read humorous novels that were very funny, but difficult to keep reading because the humor made the characters hard to sympathize with. I stopped caring about what happened to them partway through, which for me, makes any story - no matter how well written or otherwise entertaining - a tough slog.
I know there are writers who will disagree with this, and I will concur that in short works, humor that doesn't let you engage with the characters and instead mocks them *can* be effective ... but I still much prefer sympathetic humor.
Which brings me to a comment heard at one of the World Fantasy Conventions: parody only works (or works best; I cannot recall the exact wording) from a place of genuine love for the thing being parodied. This idea stuck with me, and I really enjoy it. It makes parody into a sly confederacy with the reader: here's this thing we both love, but you've got to admit, it's pretty silly, isn't it?
For me, this is why most political humor fails. Most of the time, those who engage in it make jokes at the expense of the opposite political position ... and in those words, "at the expense," comes the problem. It doesn't come from an understanding and appreciation of foibles; instead, it points fingers at and mocks the other side. In that sense, this political humor preaches to the choir; it might get laughter from people with the same alignment, but it turns off the targets.
Honestly, as a personal preference, I don't even like the humor that pokes fun at beliefs opposite mine. I'm prone to picking apart the semantics ...
In any event, affection for the target of the parody is why I had so much fun with Who Wants To Be A Hero? I grew up with Greek myths (which says disturbing things about my childhood) and devoured other mythologies ... and yes, a certain brand of reality television is my guilty pleasure. I love the skill-based competition shows: Top Chef, Project Runway, Face-Off, even America's Next Top Model, though the drama gets to be a bit much with the last one. They provide fertile ground to vent my frustrations ... do it with a wink and a smile.