I still don't understand...
Most Helpful Girl
It simply means that someone looks a mess but it can be expressed more than just someone's physical appearance/the way they dress it can also mean they're making a fool of themselves.
He's a hot mess because he's half naked, looking rachet, and dressed as a girl
Where as she's a hot mess because she's clearly had one too many to drink passed out and people were f*cling around with her
Most Helpful Guy
this may prove insightful