If you think Gumtree can be a pain, just try giving stuff away on Freecycle.
We (sadly) eventually gave up because, as you say, it seems chock-full of crazies. The idea of keeping stuff out of landfill is a good one, but offering something for free seems to make everyone think it’s intrinsically worthless and that you’re somehow providing a service by giving it away.
My favourite we had was a woman who wanted a hoover we had on offer. She mailed me to ask whether I could bring it to the bus station in town. Well, no, I couldn’t: I didn’t have a car at the time. And really, it’s a free hoover, there’s a limit as to the ends I’ll go to in order to give it away. She eventually turned up some hours after the agreed time, looking exceedingly stroppy, with three kids in tow. When presented with the hoover she said “Aren’t there any extra filters or anything with it?”. Well no, there aren’t — it’s a FREE HOOVER. She took it in the end, but seemed to be doing us a massive favour.
OTOH, we gave away a printer once (literally BNIB, due to a weird Amazon foul-up we never got them to rectify) and the guy who took that bought us a box of chocolates in return. So it’s not all bad!