They win, ChickPea. Pinterest require a link to 'the picture on my website'. That means I would have to trawl all the way through my gargantuan Merelan City thread and do over 100 forms for all my maps, just to make sure I got all of them. I just don't have the time or inclination.
They also require you to provide a link to each of the offending pins on their own website, which requires a person to register an account to be able to click on the maps to get the Pinterest page address to fill in the form properly.
Even if I registered an account just to get my maps off their pages (which I absolutely refuse to do because that's like supporting them) there's also no guarantee that the whole lot won't be re-pinned again in a week or so's time by someone else.
It seems that the only thing we can do is just let them carry on making their lists of pretty pictures, if that's what' floats their boat', while ensuring that anything else we produce has a lovely clear name on it somewhere where you'd have to cut the map into a really odd shape to get rid of it. After all, if they are making revenue out of us by using our maps to drive traffic through their site for the advertising revenue, then we can play them at their own game and have our names freely advertised along with our artwork We just have to get into the habit of marking our stuff nice and clearly, and in an attractive way.
Incidentally....
If you regularly browse for reference images and get sick of seeing nothing but a page full of images from Pinterest, you can rule them out of the search altogether by using this handy little string in the search box after whatever term your searching:
[search words] -site:pinterest.com
Voila! No more pages full of nothing but those irritating pins!
Equally, if you want to deliberately look for something on Pinterest you can use this:
[search words] +site:pinterest.com