Yea or nay: clipping fingernails and toenails? (This one really sets me off for some reason.)
My problem is when people cut their nails in the office let them fly all over the place without cleaning them up. That's the image that came to mind in the parent's comment and it grossed me out.
Essentially, if whatever you're doing involves leaving visible bits of you behind (e.g. nail cutting) please do it at home or in the bathroom at work.