To be honest, we haven't a clue, either.
But in one Spanish destination - Barcelona - a savvy hairdresser has carved a niche for himself with not one but four groovily-decorated Anthony Llobet salons, where the stylists all speak English. (Between them, they've 11 languages.)
No need for hand signals for 'more volume on top, please'. No being zooshed automatically with lacquer when you don't know how to refuse. No getting 'lost in translation' at all, in fact - which is what generally puts the fear factor in getting your hair styled overseas.
Jo sleuthed out these 'English hair salons' when in the Catalan capital at the weekend, needing to look zhooshy. Got a fabulous blow-dry (Andreas at John Frieda, are you looking nervous yet?) And can particularly recommend Fanny, at the Gotic location (in this very hip and happening area of town).
So we say: viva Anthony Llobet!
(Which is about the extent of our Espanol, unfortunately...)