The rubbing alcohol works, but our IT guys showed me a great trick that really helped my trackball. Put a tiny, tiny tiny, tiny (See where I'm going here?) tiny drop of hand sanitizer on your finger tip, or thumb tip if you use your thumb to move the track ball. Roll the track ball around and around until it stops feeling sticky from the hand sanitizer. Your trackball should work better.
Your mileage may vary depending on the age of and amount of crud embedded in the track ball well. I do carry my bb in my pocket, and I am well aware of the amount of lint that accumulates, but this trick worked very well for me.
The reason that this seems to work is because hand sanitizer has a huge amount of alcohol in it to help it do what it does. In fact there are documented cases of kids getting drunk and ending up with alcohol poisoning from licking the hand sanitizer off of their own hands.
snopes.com: Hand Sanitizer Alcohol Poisoning