Wally, I can relate. Although I'm a mere child of 63, there's no doubt that my ears' frequency response has been damaged by a half-century of live playing. I know it's the result of gigging because for most of that time I stood stage left (nowadays I
sit stage left) and today my left ear is more reliable than my right (e.g. I hold the telephone to my left ear).
For me, the greatest danger in terms of mixing and mastering is over-representation of the frequencies I don't hear well (12 KHz and up). I hear this problem in mixes made by younger ears, too, though it's caused not by hearing loss but by mastering in headphones. Headphones kind of mimic age-related hearing loss, but it's even worse since age-related loss tends to be a smooth rolloff and headphones get uneven and weird at the high end.
It would seem to make sense, then, to compensate headphones so they're flatter. However, the brain is a wonderfully adaptive organ. Over time, it will program itself to recognize what a good recording sounds like over any playback system, including headphones. Given enough repetition, your brain will eventually be able to tell you when your recording sounds right, even when the transducers aren't being honest.
As long as you can visually ascertain that you're not too hot at the very top of the spectrum, you'll be OK. A spectrum analyzer is therefore non-optional gear for the over-50s. Actually, it's recommended for the over-40s, too, because audio engineers lose their hearing faster than the general population.
At least, that used to be the case. A recent study showed a frightening percentage of teenagers have the hearing acuity of a 50-year-old, the result of constant use of earbuds at high volume. When that generation is our age, they'll be functionally deaf. Mass deafness is predicted to become a major public health issue in 30 years' time.
So for the young guys reading this: your ears are your most precious resource; protect them now!