Here's a good reason - I just pulled out an Angle LD orange ball that I purchased a while ago on Ebay. Took it to the pro shop to get some holes drilled since I needed to change the thumbhole on my spare ball and figured I'd just start fresh. Brough it home with holes and guess what I discovered? THE BALL ISN'T ROUND!!! I noticed a bit of space between the core and the cover near the fingers when I looked in the finger holes, and looked more carefully and saw that there was a large bulge in the ball - not a pimple - not a bump - but a large bulge. Kind of rolls funny too
Naaaw - I didn't bowl with it. But it sure did roll funny across my garage floor. Scared the crap out of my dog too!!
I guess next time I purchase on Ebay I'll give it a closer inspection.
Kind of makes you wonder how it ever left the factory?? Great quality control department!

The Pro Shop has probably drilled 50 balls for me - all 'spot on' perfect. The guy also has a sense of humor. My guess is he went ahead and put the holes in it just for laughs. He was probably hoping I wouldn't notice until I threw it. In any case - since I only paid 17.99 for the ball (+ shipping), it's not a big deal. Kind of funny.