Why would you not paint it? The only excuse I can imagine --if you are not a hard-core racer, and this would apply in that case anyway-- is if you dry-sail the boat (keep it on a trailer).
Here in NJ a few guys informed me of a bottom-paint trick I thought was ingenious and actually very thrifty. From new (or a bare bottom) paint on one coat of a color you don't like. This paint can be anything. I got a can of red hard-shell from a closeout. Then paint in two coats of decent ablative in the color you like. When you see the ablative wearing down till the ugly color comes through, repaint. If this only happens at the end of a season and you see a lot of, say, red, it's not a crisis because the bottom is still covered. Just paint the spots you need to, or one good coat will do it. In NJ we usually say one coat of ablative per (6-to-8-month) season, so these guys are hedging their bets well.
The only expense in this is one extra coat of bottom paint, once. With using ablative, it is ultimately much cheaper than waxing and cleaning all the time.
