Anecdote =/ Fact
If you think putting a foreign substance on the ball is "common" among pitchers, you don't know jackshit. Way too easy to get caught, and there would be ejdctions all the time. Which, as a matter of FACT, there is not.
Now, if you were to say that it's common for pitchers to scuff the ball or raise the seams, then I'd agree. Putting goop on the ball, absolutely not.
I'm really getting bored with how much smarter I am than all of you, ftr.