I think pic swapping between individuals has been overrun by the sheer volume of freely-posted nude pics on sites like flickr dot com. There, you can remain anonymous and just rake in all the comments you get. It's up to you if you want to reply and have private DMs, by which means you can get into private pic swapping. They have forums (called "groups") on pic swapping, so I assume there's enough interest there to meet what you seek here.) I see that SW has no such forums, but you could start one.