Eh, I can abide to some rules, but im an anarchist and feel if its on public domain without a watermark or copyright protection, its up for fair game to alter, mock, or infringe upon. Its like taking a picture of people in public without consent. Can it be done, yes, does it get done, yes, can you still be sprayed with bear mace for taking it without consent and refusing to delete it, yes(true story from hitchhiking). My old van and I even got starred in a documentary done by a big TV network without my consent, and the fact of being in a public place(side of the road), I retained no rights, money, or knowledge that I was being filmed until people started following me around talking about seeing the van on TV. Which then turned into a big problem cause of what the documentary was about, later having to sell the van due to it. I contacted the network and quickly got shot down by their lawyers.
I deal with a lot of ebay dealings now, and I always watermark every photo I take. I found as long as I watermark the image, it allows me to contact the person who uses my images, and ebay, to resolve the issue and have the photos removed. In this case, distributing renaissance weapons, where 95% percent of resellers on ebay use the distributors poor stock images, compared to well modeled, lighted and full detail photos, ends up getting more attention then the rest of the sellers. Of course now ebay is trying to turn into Amazon and I'm having issues with type(watermarks) on images, but nothing has stopped me so far from putting our business card in the background to avoid their new rules, and they haven't removed any previous listings of items that do contain such type watermarks.
Of course this is just my opinion.. I haven't had any legal troubles and I have to respect rules set fourth by whatever service I use even though I don't read them. I just go by the safe rule of watermark everything that goes up on internet unless you want to see it in a meme. If people get uppity cause they failed to copyright or watermark images.. I just butcher "their" work with drag queens and send it back to them until they start to adhere to protecting "their" work that their so sensitive about.