In reply to Desie:
Unfortunately, there seemsto be a pattern with sales channels, either:
A - they are really good, they increase in popularity so get overly commercialised and then end up becoming utterly useless...
or B - they are pretty good, but other channels appear, users migrate there and they end up being less and less effective...
Transformation A happened with eBay many years ago and it's now utterly appalling and best avoided.
Transformation B happened with the For Sale Forum on here. 5-6 years ago it was pretty good, however it now just doesn't get the amount of traffic that Facebook etc. do now. It's still worth posting here, but for generic items the amount of interest may be fairly low.
That leaves the Outdoor Gear Exchange group on Facebook which unfortunately is currently under going transformation A as we speak. About two years ago it was amazing but every "improvement" Facebook has introduced has been anything but. It's also now rather too big for it's own good. However, at the moment, it's probably the best option for anything still worth a bit.
I use the OGE group on a monthly basis mostly to sell climbing related books. For that, it still works well enough and I don't get too many time wasters. Unfortunately, it seems that for more generic stuff or anything that is harder to sort out delivery for, it's a bit more hit and miss.
For recycling low value items, I think it probably varies a bit more by local area, so I can't really comment. I often manage to give away stuff via the local Mountaineering Club's Facebook page.