My wife has a problem with keeping her grips clean.  She will clean them with alcohol and  only needs to throw 8 to 10 balls and they are dirty again.  Her hands are not dirty. Has anyone else experienced this?

Sounds like the bowling center could be cleaner.  Having said that, there is probably dust, etc. flying around in the air through the heating and air conditioning in every bowling center that ends up settling on the lanes.  After that it ends up on the fingers and thus the finger inserts. 

Give her an old toothbrush and when she cleans her ball surface she can keep the inserts looking nice again. 

1- Center very clean
2- No one else has the problem
3- Wife has clean hands

Either she has the new kind of inserts that extract microscopic dirt from her fingers, thus making them appear clean; OR the mechanic in the back is applying dirt to her inserts before sending the ball back...

This may remain a mystery for years to come...

Wouldn't suggest cleaning grips with acetone.  Tends to "dissolve" them..    maybe this us why they are picking up dirt...soft and tacky now.