I sold my least-used buggy on ebay to make some money, the buyer collected yesterday.
On the auction I'd put that the buggy was in used condition, and there was some wear to the wheels, I was happy to end up getting more than I'd hoped for it! The buyer came and had a look, and declared that she wasn't going to pay as much for it as "it clearly had been used" - I said "yes, I had sold it as 'used'" - she said "look at the wheels, they are worn", I said "yes, that was made clear in the description", I had even photographed the wheels and put them on the auction so buyers could see the 'wear'.
After a while she agreed to pay and took it, I was a bit peeved though, the buggy had been used a dozen times, maximum, and had solid rubber wheels, which I had dry-brushed and wiped clean with wet wipes (along with the rest of the buggy so it would be in the best shape) but still had some light 'dimpling'.
For local pick-up I never allow cash on collection. I always make them pay with Paypal before collecting. Stops them being able to mess you around by not turning up, changing their mind, etc, and haggling at the door.
It also protects them. If you are trying to sell them an old pile of pants of a pushchair, they can refuse to take it and ask for a refund, and if you don't, they can open a case with paypal which they can escalate to a claim. Its unlikely they'd do this unless they were extremely dissatisfied and adamant it was significantly not as described.
A serious buyer will not object to paying before they've seen the goods - in fact most eBay you do that. I think it leaves you less at risk of these little niggles...