this is terrible flirting

Absolutely.

Men are not clueless

A LOT of us are, though..

smiling at us or being nice to us is not her flirting. It is her being nice because society has told women they have to be that way all the time.

Usually correct, though sometimes it IS and other times it's just her being nice voluntarily. Such is the mysteries of interpersonal interaction!

women have to use their adult voices

Boo! Adulting sucks! /j