I have been publishing with them. I am a poet on my fourth book.
Initially, PublishAmerica is a POD press (Publish On Demand). They make no bones about it.
They make books and don't charge up front for publication. The books look good. They make sure a listing of your books gets to every on-line bookstore on Earth. They will distribute profitable books to major full-service bookstores. The problem is their royalty payments are unreliable. But I have found that the payments by the book stores is also completely unreliable. I think that's the problem with the industry. I never know how many of my books have actually sold.
They don't market your books really. They don't arrange glamorous book tours. People who believe puiblishers do that are dreamers.
They rely on authors to buy their own books for distribution or sales. That's the vanity press aspect of it. I have spent hundreds for books to give out to bookstores and libraries. But there is no limit to the press run, the book is in press indefintely and listed in the right places with ISBN number.
If you want to make money for your publication you will be out of luck. Very few make any money from publishing poetry. The rule is, in my opinion, we have to pay our audience to read our stuff. But keeping this in mind, PublishAmerica is definetly NOT a scam, any more than Lilly is.