I used the Tamiya airbrush thinner as intended just once... and could tell it had acetone in it, but didn't think much of it.
Since I use acrylics 99% of the time (and Testor's metalizers for the rest) I can clean my airbrush with a wide variety of cleaners: alcohol (denatured or isopropyl), Vallejo airbrush cleaner or the Iwata-Medea Airbrush Cleaner. All work great. For the occasional tough residue, I'll spray less than half an airbrush cup full of acetone.