They're usually hidden behind layers of LLCs and DBAs, so not really; there's not a big website that says "Hey, we just steal whatever we can". If you trace the threads back to "online lead generation experts" or "internet marketing specialists", you'll find lots of such enterprises.
In my case, most of the active properties I knew are offline (though their proprietors are still rich). One guy was trying to be Tim Ferriss and had a membership site that promised to teach users how to get rich working no more than 4 hours a day. He had about 2 dozen other sites generating some income here or there, but I don't remember any others. They were hosted on a rack with 3 FreeBSD servers running in the corner of his office that some contractor had set up years earlier.
One guy was selling really bad eBay listing management software. He also had sites meant to ease the process of applying for government grants, a site that referred patients to audiologists for new hearing aids (which resulted in a lawsuit from the competitor that he had ripped off), and others.
Although all of these projects were objectively terrible and not competitive with the good products in each field, these guys almost undoubtedly made way more money than the programmers of the products they're trying to copy because they had much better SEO and spam game. While the dev who builds decent products is spending his free time thinking of the amazing features he's going to build and how much his users will appreciate them, the career spammer is thinking about which of his spam sites he needs to swap links with next so that Google doesn't detect the link ring and decrease the PageRank, and how he needs to add another minimum wage lackey to keep up with all the astroturfing they need to do.
I know of several similar schemes. They aren't the edgy startups we hear about here on HN, but the proprietors end up making quite the pretty penny off these things, despite the fact that none of them have any interest in the subject matter, nor any technical skill. They spam and rake in the dough, getting their tech work done by offshore contractors on oDesk if they can't find a naive local student who'll work only for promises of equity.
The moral of the story is that devs need to spend their time getting access to a network of sites that make it easy to gain PageRank for any desired term and tapping good astroturfing resources instead of working on features. It's really discouraging as a tech entrepreneur trying to provide quality products.