Replying to an old thread because 1) its hilarious, no less than 5 different posts caused LOLs, abd 2) I have relevant new information!
There is a real, scientifically verifiable reason removing the stamp can actually affect disc performance: by making it look and feel sleeker, you may subconsciously (perhaps consciously as well) throw it harder or with more spin, because it feels like that's how you SHOULD throw it.
You're going to do best when you have positive feelings towards the discs you use. When choosing what to dye on to a disc, I collect all the pictures I like, then (for drivers and most midranges) select for the images that make me want to throw them hard with lots of snap. Stylized pictures of birds or dragons or other things that fly are always good choices. American Indian artwork from tribes along the west coast produce some of my favorites. For putters I pick images that make me feel like they belong in the basket. A stencil of Elvis's face, or a chili pepper (Guatemalan insanity pepper style =) work for me, for whatever reason.
I've found that the SIZE of the picture is perhaps even more important than the content. Making it too large is a common rookie mistake, don't be afraid to leave lots of negative space around the "wing." I usually won't make anything taller than half of the overall disc diameter. Pictures that form something close to a circle are best, and they need to be as perfectly centered as you can get them. Freehand probably won't cut it, I actually attach a sharpie to the drawing end of a compass to do an outside border, so I'm guaranteed a perfectly centered perfect circle. Asymmetrical designs can work too, of course, but I don't know of any guidelines other than "you'll know it when you see it."
Obviously your mileage may vary, but experiment and find a motif that works for you. There are a million pictures online to choose from, as simple or as detailed as your artistic skill (or lack thereof) requires. Done right, the performance gains are not negligible. Plus, everyone you come across on the course will compliment your style, because they're all too lazy to do it themselves!