Yeah I've had this happen to me a few times. I usually just walk away during the meetup, then the buyer tells me to stop and eventually pays up.
In all my years selling, I got flaked in person for the first time late last year. Did a Kijiji meetup at Fairview, the buyer works at that Audi showroom down the street by the 404/401. First he tried to make me wait while we had lunch, then when we met in front of the Apple store I gave him the clothes and he asked if I had a bag?! right then I knew this meetup was going to be BS. You DROVE here from work down the street and you're asking for a bag? he then asked for a receipt, which I didn't have since the items were also 10 years old. He didn't even checked the product and then said because I didn't have a receipt or a bag that he'll pass.
I went up to his face and cursed him out right there in the mall and walked away. I was really pissed because I had got injured falling down the stairs in my place just a week earlier, so to go by my storage unit, get the clothes, then come do the meetup was a little painful mobility wise and then add on the time wasted.