We bought some square and some rectangular pulls for bathroom cabinets from Restoration Hardware. In addition to the the drill hole and regular screw attachment these pulls had sharp points on two sides that were meant to embed in the cabinet surface to keep the pulls from going askew. Our cabinet installer attached all this hardware so I'm not sure how it is done but none of these pulls seem off or crooked at all. HTH.

I also have some square (mission style) knobs from Restoration Hardware... have been installed for over three years now with no problems.

Loctite.

Thanks. Like the Loctite idea. I found some round knobs with a raised diamond shape and matching pulls, that I really like (they're Amerock) and since it's not a square shape, I figure if a diamond gets a bit of whack it won't be so noticeable as to send me over the edge!

Does loctite really work well? I've been going round and round with a friend of mine who's in love with oval knobs but I think they'd drive her crazy if they won't stay put. These are plain glass so they don't have any bumps or points to help them stay put.

There are two types of loctite. One is permanent. One allows you with some force to loosen it. Or you could just use a few drops of crazy glue on the threads. Either way you are just bonding the threaded bolt to the handle, the whole thing can spin as one if you don't tighten it really well after you apply these to the threads.