I always assume people doing this are unhinged/crazy and I definitely don't want to deal with that.
Sometimes they look nice enough.
Usually what happens is myself and everyone else on the train look at each other, have a shared look of "Morons? Am I right?" and then when that person leaves, we all share a group laugh.
So I guess what I'd say is, if you do this, know that everyone is laughing at you. If you say you don't care, that's a lie, you do care, that's why you're doing what you're doing. This is not positive attention, this is negative attention. Please take a moment and reflect to be a force for positivity and not negativity.