I've had some gentleman say they were reticent to share their age with me because they worried I might elect not to see them. I have no idea where they would get that impression! I'm not sure if they've had that experience in the past, or if it's just a little of their own insecurity creeping in. I would never refuse someone on age, even on the younger end, if they were able to present themselves in a way that assured me we would be compatible.
On another note, I think it's totally unnecessary for a potential client to say "I'm 60 but am regularly mistaken for 40" or "I'm 55 but have the heart of a 25-year-old"... Probably just a weird personal preference here, but I like to be with someone (male or female) who is comfortable with and appreciates their age. I don't assume a slightly more advanced age translates to grumpiness and lack of energy. Clearly, if they are contacting me, they like to have a good time!
Besides that, there are lots of benefits to maturity. Like a loss of interest in playstation