It's very naughty when people do it, but I don't have that many pix that are shit-hot, so it doesn't often happen to me - that I'm aware of! I've only ever flogged a few pix (tho I guess that's not bad as I don't try to sell 'em!) Must be really bad when you're relying on sales to earn a living.
It only bothers me if it's for commercial use. But so far it hasn't bothered me enough to do anything other than not (generally) post high enough res to print decently. For anything else, I'd ideally like a credit, but....
I can't imagine stopping posting them online anyway, as the web's the only place anyone sees my pix & I don't have the time to set up my own site - let alone do it in a way that would protect the images as much/little as you can.
love
Moth