What a 0/5 rating means
On the comedogenic scale, a 0 means it will not clog pores for essentially anyone, including very acne-prone skin. That places Acetone in the range most people, including many with acne-prone skin, tolerate well.
One thing the number cannot tell you is concentration. Ingredients are listed in descending order, so Acetone near the end of a label is present in tiny amounts and matters far less than the same ingredient near the top.
About Acetone
It is a solvent used to dissolve other ingredients or aid drying. A stripping solvent rated 0 for clogging but a maximum 5 for irritancy.
Acetone in makeup and skincare
It is used in liquid liners, nail products, and some cleansers. Its irritancy is rated separately at 5/5, which is worth noting for sensitive or reactive skin.