If anyone has any confusion as to why I've put watermarks on even the worst of my art, here's the reason; I've found my picture being used on a number of websites, illegally stolen from me. I've had one of my best pieces distributed by a framing company, a fetish piece used on a medical paraphillia page (which, to be fair, would have been perfectly fine if they'd just asked), and another piece containing an underwear-clad body on (of all things) a thrush medical page. The worst was finding myself on a Spanish porn site, with no contact address to get rid of it.
If people asked, the majority of times I wouldn't mind at all. It's great publicity, but that's me in a lot of pictures. I do not have thrush (or any other embarrassing disease), and I most certainly am not such a slut that I'd willingly be masturbation material for a country inhabited by people I statistically have problems with (not racism, just the vast majority of perverts trying to break up my marriage or do things on camera for them are from the Spanish-speaking countries).
For this reason, I've had it. I can't afford a lawyer, I've been forced to delete a lot of my best and time consuming work, and even petitioned Google to delete a lot of images that can still be searched for (for far, no word back). Because of thieves and perverts, I can no longer create art that I both enjoy and am somewhat good at. It's an awful situation to be in, so as a precaution, I've watermarked most of my content on the site. Those that cannot have been hidden from non-members, and the remaining are frankly too crap for anyone to use.
That said, this is a brilliant lesson to not just me, but all artists; even if you don't think you work is good enough, people WILL use it. Everyone should at least watermark all work, especially those containing nudity.