More and more vanity and self-publishing companies are using trade imprints to lure writers to their sites with the writers hoping that their work will be wanted in the trade imprint at no cost to them. However (and you knew this was coming), the vanity and self-publishing companies are using this as a form of bait and switch. Sure, they might even actually print one or more books with their trade imprint as an investment to give it credibility, but the odds are those have already been published. Odds are they don't really care if their investment books were carried by any brick and mortar bookstores because they've accomplished their goal. They've got a Judas goat to lead other writers into their den. Once the writer is led in, they read over the manuscript, then state it's just not quite good enough for their trade imprint. But it's a good manuscript and they think it could do well as a self-published or vanity published book. At that point, the writer has heard "IT'S A GOOD BOOK." They said so. Not great, but good, so why not invest in the book just to show them that it can sell and make back the money? After all, they said it's good and they're publishers who are careful about what they invest in publishing.
It's faulty logic, but it works because it ignores reality by not mentioning details like distribution, marketing, promotion, and sales to retailers. So please don't fall for this. Don't let your friends be taken, either. Point out that if it's not good enough for trade publishing (which means no investment of money, whatsoever, by the author), then maybe the manuscript needs more polishing and craft before it's truly ready or the niche it falls into simply isn't large enough to produce the profits needed to justify publication.