It's funny really isn't it - I fully sympathise - I do a sheltered accommodation complex for a dozen or so oldies and they can be sweetness and light or really irritating!
Another "oldie" I do is Mr. F________ (No, really!

) in a close of six houses where I do four of them and I was recommended to him by another neighbour. Anyhoo it turns out he knew my father when they were kids before WW2 so a nice connection I thought.
Trouble is he's been getting grumpier and grumpier over the last year or so... first it's the wfp/trad switch over (oxidised 1980's single glazed ali windows) which now come up well. Then he wipes around the upvc of his new front door while I do the windows to the side; then I get told his (manky, cruddy, minging ali) patio doors leak so could I be careful.
Then "hang on while I move the plant pots" (I offer to move them but no he can do it - like a snail); then mind your hose doesn't pull another stone out of the patio wall like it did last summer; then mind the hole in the front window (where some chav shot thru' with an airgun five years ago) ..... and can you put the doormat back when you've finished (I always do)
Now he's becoming rude - I always knock and start cleaning and last time it was "Oh, it's you!" accompanied by rolling eyes; to which I reply through gritted teeth "You don't sound as if you appreciate me coming Mr. F_____________" "No, no I'll open the gate (at snails pace)"
Finally I knock for payment..."I s'pose you want payin' now!"
"Yes please that would be nice!" I respond cheerily.
I'm on the point of ditching the old goat! If it wasn't for the recommend and the history with my dad and the fact that when I'm feeling less sensitive I reflect that if I was 80+ with a crippled wife then I'd prolly be a bit grumpy too!
I think in the new year I'll come out with "This arrangement isn't really working is it Mr.F?"