There’s a couple of scams you see on eBay, the best way to avoid them is to take payment via PP and send via courier, it’s when you deviate from that you run into trouble. (Well apart from cash on collection I suppose).
Once you get past the fraudulent buyer and into dodgy buyer bit it gets harder – be VERY clear about anything detrimental, however minor or you’re opening yourself up to the ‘partical refund’ types – they’ll contact you a few days after purchase “oh the tyres are worn” “the fork needs a service” “it’s got scratches” etc etc etc – they’ll ‘kindly’ offer not to hit you with negative feedback and whatever else if only you refund the value so you sell a shock for £200 and they want £80 for a service (even though a shock with a fresh invoice for a service would be worth more” or a pair of tyres at RRP etc.
I’ve been done a few times like that – now my stance is “sorry it’s not what you expected, please return for a full refund”. They still argue.
I take photos of everything including serial numbers, I don’t want someone’s knackered kit back in place of my stuff because they’re trying to pull fast one.