Nylon tends to dissolve in acetone.
If your acetone has any water in it (most OTC has a little), there will be some of your goods in the bowl. which you could reclaim by letting it evaporate, but now it will also have some nylon dissolved in it. There could even be some nylon stuck on the bottom of the stuff in your "filter". (Cotton or paper-based filters are preferred.)
Plus, nylon panty-hose aren't very fine filters. If you want to be washing your shit properly, it should be thoroughly crushed, and this wouldn't do very well in a coarse filter..
3 Pieces of Advice:
***Dry your acetone with baked/microwaved epsom salts. (Look it up.)
**Pulverize your street-bought gear, put it in a bowl, and utilize the panning method. (Or, essentially, just add acetone, mix for a second, let it settle, then carefully decant-off all of the acetone.) Do this twice.
*Give recrystallization a try sometime..