Get a plastic jar (like a spice jar) and pour in rubbing alcohol and table salt. Put dirty pipe in the jar and put the lid on it. Shake it for a couple of minutes, rinse pipe under warm water, dry and done. You can re-use the alcohol and salt mixture for years! Basically it is the same as this video but without all the taping off.

I've used acetone & I hate it.

whiskey for a little while, everything comes out easily with a Qtip. Acetone is the first turn off for me, I can't tolerate the fumes and it's not good to pour down the drain!

and cheap.Done it for years.