I use the Q-tip as well. Rubbing alcohol will evaporate quickly so it should be good. Although, I just dampen the Q-tip and clean the visible portion of the trackball. Then, once dry, I move the ball a bit and repeat the process.
The process above helped fix a "sticky" trackball!
I just tried this and it works very easily. Got a little scared as I was not sure if I paid close enough attention to how I took it apart! Looks great and rolls even better as it seemed mine would not always roll on command!