I have to say I've thought about this quite a bit before, I'm not so worried about my physique as I do keep in reasonable shape but have the inevitable middle aged few pounds extra on the gut; hair loss and glasses.
I remember when I was only 34 asking myself if I was too old to punt with girls in their teens and early 20's but it hasn't stopped me and as quoted above it's a business deal, how I wish I was 34 now!
If the girl has a major issue with your age or looks then they are in the wrong job or need to specify restrictions on their profile, when you add up what some of these girls make in a week for working a few days it's bloody good money and we all have to put up with shit we don't like at work to get on, that's life.
For me I like to punt with girls 18-25 or 30 top and they have to be slim and good looking, basically if i'm paying good money then I want to see a girl that I'd never pull in the pub, if I wanted something in my league then I'd be in a relationship.
I think most girls are actually OK with middle age punters and half their business is probably with guys like us, what's probably most important to them is what Smiths says above and you are on time; clean and have the correct money.
For me the question is more to do with at what age should you stop punting especially when you are going for younger girls, for instance when I'm finally 75 should I see a girl who is 25 and a third of my age, there has to be a limit at which it's starts getting "wrong"?