It still amazes/facinates me that people get told off by their missus for spending money on their car!
If I earn the money, Ill spend it on what ever the fuck I want!
My missus is the same, she earns it, she spends it.
If I want to blow all my cash on the car, I will, and she wont bat an eyelid!

As for hair dressers, if she wants to go, she pays for it, pretty simple really