I worked for a vanity publisher that would publish literally anything you sent to them. But you had to buy all of the books yourself. They did nothing to help promote your book. They would cold ship books to bookstores along with a bill, most either refused the shipments, or dumped them.

I did the layout for children's books. And let me tell you, when I say they would publish anything I mean anything. There was a book about snails, but none of the "snails" had shells, and they all looked like penises. There were a couple kids science books that were factually incorrect. We were not allowed to correct or change anything.