First ball out of my bag right now is a blem. Silver Streak Solid, marked with a B. The only thing I can see wrong with the ball is a slight white line extending about 1 inch out of the pin - looks almost like a crack, but it's a pigmentation flaw. So, as 1Fife said, color and engraving mistakes = no problem. Long (or short) pin = no problem IF YOU know what to do with it. For some drills very short pins might be just the ticket. Same for high or low top wts. - avoid them unless you know what you're doing. I'd avoid anything with pitting however.
--------------------
"Things fall apart; the center cannot hold; mere anarchy is loosed upon the world,"
I'm Ragnar Floggurass, and I approve this message