Looks like a lot of old tat on those FB pages.
I joined a few, but decide against advertising, as it is full of young mums selling rubbish for 2 or 3 quid and haggling over 50 pence
and lots of "I need a joiner/Gardiner/ blah blah" all ending in the word cheap
I have seen loads of sales fall apart when they agree a price on an item, then they go looking for a Man with van, to move it and realise the cost doubles.
so I will avoid it for now