As a general rule, you should clean or polish your ball after 6-12 games of bowling. If you’ve been bowling on dry conditions, heat and friction will make your ball surface stickier than normal and it will hook more than you’re used to. Conversely, if you’ve been bowling on wet lanes, the oil gets into the ball surface and takes away its hooking ability.
Have you ever wondered why your ball isn’t hooking, even though you’re doing everything you’ve always done? It’s very possible you’ve gone too long without cleaning it and the surface can’t grab the lane anymore.
Many bowlers clean or polish after every series, and definitely before league or tournament play, and those are the guys who usually dominate their leagues. Most league members bowl hundreds of games before polishing, and some will never polish. These people are often inconsistent, bowling one well week and terribly the next.
You can buy your own bowling-ball cleaner inexpensively, or most pro shops will polish your ball for a low price. To maintain the quality of your arsenal, try to clean the ball at least every 12 games.