Sure you do. If you behave to the detriment of one gender but not another, that's sexism. You then say "sorry, didn't mean that", and change your behaviour now that you know.

sure, assuming someone has been crying is dumb. noticing a change of appearance is something women want you to do when it's a positive thing ie. new haircut. but if it's negative it's probably best to reword what you're saying in a more positive way.

but you can talk to men how you want, they won't care.

so yes you have to behave differently to both genders.

I said "to the detriment of", not "differently", for a start.

so treating both genders equally doesn't always end in equality.

Indeed it doesn't!

However, the reasoning for that is interesting - the primary reasons women get more upset when you speak about their appearance negatively when compared to men is that women constantly have it drilled into them that their appearance is one of the most important things about them, from a relatively early age. We have a combination of media and other people who do that - often even other women.

It's something to be solved, but as the situation stands right now, yeah, criticising women on their dress/makeup/haircut only serves to further that - because women have generally already had significantly different experiences than men by the time you meet them.

"Detriment" varies and apparently has a strong gender correlation though.