I was ordering Maestrowork's novel at my local (large) independent bookstore and happened to see a note taped near the register that said "Don't order from these publishers." From my perspective it was upside down so couldn't get them all, but three of them were Xlibris, iUniverse and 1st Books. I asked the clerk what would get a publisher on this list and she said they were usually POD or vanity publishers, and the store wouldn't order from them because they don't take returns or they're difficult to deal with.
Just a heads up on these publishers from one store. If it's their experience, it might be the same in other places, too.