If the weathered look is what yr going for, then, ironically, you might be pleased. (One of my brothers took an old leather jacket, rolled it up, and ran back and forth over it on the wet ground with his truck about 30 times... and it came out with a *very* nice, weatherbeaten patina after it dried back out.) Also, if they are lambskin and they're too small, this can be an effective way to stretch them -- get them wet, and then stretch the living hell out of them. (If you *don't* stretch them when they are wet, they will probably get a little smaller.)
But, nooooo they are not "waterproof", lol. Not any more than any other leather thing is waterproof!