I used to use Tumblr where reblogged loads of pictures, mainly adult ones. 1) I'm wondering, how often are pictures that floats around the internet with thousands of views/likes/shares copyrighted? 2) Can I get in trouble for scraping bunch of pictures in adult tumblr blogs and reposting them on my site? I just don't understand how picture websites find their content without breaching any copyright.
Always. Every picture, article and other piece of content is the property of its creator and, unless they specifically state that it is public domain content or provide another usage license, it's copyrighted material. Yes. More often than not (in the amateur market), they don't. They simply rely on the fact that few people bother to chase them about it. Speaking personally, I've had three requests for picture removals in over 20 years online, though I wasn't running picture sites when I got them. The last one was this weekend just gone: I'd used a random image of chilli sauce (found on page xx of a Google search, as usual) on a site and the owner asked me to take it down. I always post a "no quibble" removal policy on any site I run (i.e. ask and it'll be removed without question, regardless of the reason), though that's still no protection if someone really wanted to inflict pain through legal means. In general, it means they send an email and you take the pic down... no guarantees, though.
Thanks, especially for bringing up your personal experience! I don't think I'll take the chance though.