My preference for title depends on what the product is. If it's mainly rules/crunchy bits, such as the splat books, I like it to be fairly short and directly relate to the subject. The more work I have to do, to figure out what the heck it's about, the more I'm apt to be turned off. I kinda figure that if the name is that obscure, the rules and mechanics are liable to be even worse to figure out. Think technical writing. You want the mechanics to be as clear, concise and unambiguous as possible, and trying too hard for cute titles or names can kill that PDQ. For me, "Savage Species" is a better title that "Tooth and Claw" or "Claw, Claw, Bite" in that it relates much more directly to what the book is about.
For modules or world books, I still like the short, but exotic and/or mysterious can work here, if it's well done. These are much more like short story or novel titles. A well turned phrase, even if a bit obscure, can indicate that the contents are equally well written. Since I'm probably gonna rework some stuff to fit my group, I'm a little more tolerant of the mechanics, if the story, personalities, etc., are interesting.