Good question.
I had a few regulars back in London who would always tip me. Basically they would give me my fee and what they called my "little extra".
On the whole I would say I would easily get tipped at least 3 times a week, apart from those regulars also new clients left tips. Plus quite a few clients bringing all sorts of wine, champagne, flowers, chocolate blablabla
When I started touring I had few clients who left very nice tips. But few. I don't expect tips so it's always nice but it's really a "surprise" money. I still have a few guys bringing champagne, wine and chocolates (I don't really like chocolates so that's perfect for hotel maids haha). I had guys bring me coffee, books, newspapers, breakfast, fags (ok I asked lol), fruit juice and all sorts of things. At the moment I'm sort of asking them please do not bring alcohol as I'm trying to drink less. Because at some point I had over a dozen of bottles coming just from clients