Personally, it doesn't really bother me that much if its a photo I'm wanting criticism on. If it's a photo I'm really proud of though, I would be slightly offended. But I'd probably get over it and then copy their idea if I liked it. And if I hate it, well then I know what I don't like
I liken it to buying a dress for a big party. You have to try on a couple of dresses that you think are going to look awful on you,,, just to see. You might get a nice surprise. And if it looks ugly, well you just forget about it.
But you have to remember that this is the internet and any old person can come into these boards and steal these images if they want. So I always think about which pics I put up. If I don't want them stolen I don't put them up. But stealing pics is different to editing them.