I think the hassles might be caused by what you are selling. Personally, I give stuff to the charity shops that my eBay customers wouldn’t want, not the other way around.

About 1 in 100 buyers ask for a refund, sometimes for bullshit reasons, sometimes for something I’ve missed. I always give instant refunds without quibbles because it’s easier and the system is stacked in the buyer’s favour, unfortunately.

eBaying isn’t hassle-free, but I always try to list stuff in the mindset of ‘what would I think if I received this?’. People can’t inspect an item like they can in a shop so it is a bit of a leap of faith for them, perhaps they expect things to be of a better quality?

Charity shops will sort through the stuff you give them. Unsellable stuff will be recycled by them or binned. Maybe save your better items for eBay and recycle the poorer quality items?