I think a big part of the reason audiences feel safe in finding this funny (and not funny in the sense of dark comedy, which is more openly transgressive) is (and this is a better phrasing of what I was going for in my OP) that the stuff the Chameleon does is so out-there that for most people they just don't associate it with real-life things like consent issues. A guy wearing a rubber-mask to flawlessly impersonate someone (let alone, as in the JLU episode, literally swapping bodies) just doesn't happen; it's absurd on the face of it.