If it's a particularly good pic for whatever purpose people swipe them and use them anyway (sometimes they'll even bother to remove the watermark, while I was looking up something about video editing the other day I came across one advising people on how to remove watermarks in videos and I had several bad thoughts towards the author of that) >_<
Of course they do. That's not the point. When you label it, you have established without a doubt that the work is yours and that they are infringing .It is very easy to remove a watermark. I could do it with my eyes closed. LOL! Some people (not all) will hesitate to use a watermarked image because they know it is wrong.
I probably should have clarified that I generally advise along similar lines to you (to watermark things), was more throwing it out there because I wanted to express annoyance over people who go out of their way to try to remove other people's watermarks and also because I have known people who were genuinely shocked that watermarking didn't render their works unstealable :)
Thanks! i like your creative logo! :-)