I've inadvertantly made comments that could be construed as insulting.

Inadvertantly because I didn't realise there was a coachload of blind (I do beg the pardon of the PC brigade, make that visually challenged) people in the audience. The only person who (sort of) complained was the organiser, the optically disadvantaged lot thought I was taking the piss and loved it, which corresponds with experiences remarked above.
It wasn't very insulting. I was introducing a song made popular by two blind singers and asked the audience to draw their own conclusions.
I suspect that people with real problems are not very touchy about them, and enjoy a joke against themselves as much as any sensible person would.

Yellow girls are admired more than black OR white girls in most shanties. Or maybe that is only my impression.