The publishing waters are teeming with sharks. These days especially, anyone with a laptop, a printer, and access to photo images can launch a publishing site. So how do you tell the good guys from the bad? What's a good risk vs. a bad risk? Depends on what you're looking for.
Common sense tells you to do your research. Check out previous sales figures, talk to other authors who've been published with the house, scour their website and check their online presence. How approachable are they? What kind of education do their editors have? Is there an art department for covers or is it the owner pulling stuff off some stock photo website? Most important of all, don't ignore your inner voice that might warn you against signing on the dotted line.
But what if you're considering selling your work to a company that just opened its doors? Research on sales figures, previously published authors, and online presence can be hard to come by. And yeah. Even the big boys started out small at some time. So you might be willing to take the risk when it comes to a new publisher. And that's okay. Just go into it with your eyes wide open. Be aware you're probably going to get burned, the company probably won't last long, and you'll wind up fighting to regain your rights to your own book, a book few other publishers will want because it's already been released. If it still means that much to you to be published, no matter how the stats stack up, go for it.
Just don't blame bad karma, bad luck, or any other mystical mojo when the publisher suddenly disappears from the Internet. You swam with the sharks. You lost a limb. Learn your lesson, pick up what's left of your dignity and take your talent elsewhere.