So many scammers on Facebook, but without trying to hijack this thread, my current bugbear is with Vinted.
Saw and bought a pair of Veja trainers on Vinted for a bargain price of £30 (I know, I know - looking back it was obvs too good to be true!).
A couple of days after the payment went through, got an alert saying that the trainers had been shipped. I was able to get the Yodel tracking number and see that it was due to arrive on a particular date - it even said on Yodel 'out for delivery'. But then it didn't arrive on that date and it changed to 'it's on the way'.
When I questioned that with Yodel, they said I needed to go back to the seller, as the issue was with them. Well, when I did, the seller's profile was blocked (apparently this happens with scammers) and they weren't replying.
Initially Vinted were saying I'd have to wait a month for my refund, but I kept messaging them and they actually refunded it in full early (obvs because they realised it was a scammer).
The interesting thing was that at that time, there were LOADS of accounts with really random usernames (think eiofbdmc39dj) selling Veja trainers that looked brand new and with identical backgrounds that looked suspiciously like a shop!
I think Vinted have cracked down on these scam sellers now, because a lot of them have disappeared, but you definitely need to be careful buying on Vinted too!