We used acetone to clean paint brushes and other sprayer parts for years, until many of them were made with plastic. Acetone and plastic do not mix. We had plastic light lens, when we cleaned the overspray, that almost "melted" from the acetone.
There are only certain plastics that Acetone attacks violently. One of the big ones is ABS. You can actually use acetone as a glue to reattach broken ABS pieces.