These stamps are cheap, very cheap. You need to rub them with an eraser and wash them off to get even a half decent image. I have 8 of them, someone I know has that many as well, and all the stamps in this line have the same problem. The stamping ink beads up on the stamp and creates a dotted image instead of the crisp lines you see.
But for $1.89, what do you really expect? They're small, they're cute, and they come with a line of bling on the packaging. Just be prepared to spend some time (a lot of time) going over your image with a pen before you can colour it or use it on a project.