As I see it the biggest problem is respectful to others. Like all of you I have seen people do some disgusting things on the plane.

The Smell of the nail polish and the nail polish remover is the problem here IMHO.

Trimming a broken nail, OK. Cutting toenails not OK

Chewing tobacco not OK.

Be polite and limit your burping, drooling etc, but you can’t always control that.

I also have a problem with the Nail polish remover since it is flammable. IIRC it does have a quite high flash point, but I did not think you could bring flammables onto a plane.

As someone already pointed out, there are things that should be done at home. Putting on finger nail polish is one of them.