My other half wears hearing aids and is older than 69 (although still works and hasn't yet drawn any pension) yes it's a pain to live with but this last month I've had horrendous issues with wax following a bad cold and now understand what it must be like living with partial hearing. It's very disconnecting and annoying.
I have quite a mixture of ages clients and a twat is a twat nothing to do with age. I did have a client who I found difficult because whenever we met which was outcall in a quiet hotel, he would constantly ask me to repeat myself. With time and my encouragement he did go have his ears syringe, and seeing me helped him start looking after himself again. Yes he did fall into your OAP bracket, and he did have performance issues. He treated me decently, he was gentle and polite so I returned the respect by being patient and understanding.
Regards the steep stairs I've had much younger clients struggle, and some older much fitter than most. My OH manages the steep stairs in our home daily despite being a blue badge holder, and having a mangled foot (his disability).
Disability or not in my experience is very individual and not related to age.