Isn't that more about the content of what they're saying (and the context of how often they've said similar things) than how they're saying it though?

EDIT: Unpacking that a bit, wouldn't it have to be one of:
1) The accusations are incorrect
2) The accusations are correct, but petty compared to how narky they get
3) The accusations are correct and serious

Now in (1) it's the content that's the issue and it makes sense not to pay much attention any more, and in (3) you're the one at fault, but 2 is more ambiguous. Still, I think I personally would still take the criticisms on board if they're correct, I'd just not be very gracious about it, the same way I react when Cam rudely corrects my grammar. The fact he's being rude doesn't change the fact that my grammar is wrong. And racism is much more harmful than bad grammar!

Also, you still didn't answer my question :P