I was the hairdresser (the girl who washes the hair amongst other stuff) and a tip is always more than welcomed but never expected. Some do, some don't.
I guess when i go to the hairdressers now, or, to a restaurant, then i decide if the service has been good and tip accordingly. It also depends whether i feel i have been overcharged for the service in the first place, if so, then i tend to think, nah, they've had enough out of me.
I'll only tip if I get a 'muff nudge' (the light brushing of my favourite female hairdresser's crotch against my elbow while she leans forward to cut my hair) :-)
I visit my Hairdresser every 3 weeks and always leave a Tip. Have been going to same one now for about 12 yrs and satisfied with the Service given, always, as they are pleasant.
I ONLY ever tip when I want to. I don't buy into the whole 'tipping' thing. If they did a good job or were friendly and helpful, I tip. If they just did their job then I just pay.
I did a job for a barrister, the final bill was for over £600-00. He gave me a cheque, then reached in his pocket & said "have a drink on me" as he handed me some money....It was 2 quid....