POD just want your fees and they don't promote your book at all. In fact even legitimate publishers have a very limited budget for promotion of your book. The thinking these days is that the writer is the one who promotes the book!
Sorry to be the bearer of bad news, but publishing is in a very tight situation these days.... books are just flooding the market and the demand is not that great.
POD is for people who are willing to pay to see their work in print. It's up to the author to sell them.