Really, People?!

I now have an addition to my "I can't believe they did/said that on the train": clipping fingernails. Seriously? So gross. The woman in the seat behind me was actually clipping her nails on the train--not over anything so she could throw the clippings away, but actually onto the floor. I was so grossed out that I almost said something to her. I just settled for giving her a couple of dirty looks. And what would I say? You are grossing me out? I can't believe you think what you are doing is appropriate? Are you seriously not using a trash bag? Any other ideas?