I've been lucky so far but usually limit my travel by 30 minutes. Either close to the office or close to the house, or have them meet somewhere in between.
I did buy a sub from a kid going to college last year and didn't test it, since he was only a 2 miles from the house and he gave me his word I took a chance. Got home... Blown sub. Kid tried to dodge me for 3 days, called his cell, got his home address and number, called his house and left messages.
Then waited for 2 days to see if anyone would call back. I then called again and got his mom, she freaked on me stating we are christians and why do you keep calling me blah blah blah like she was scared. I very calmly, mame your son sold me a sub with the promise that it worked and I tested the sub and it has been blown. IF you are indeed christians as you say then you would not be dodging me and would have promptly returned my calls to make this right and do the right thing as christians. Now what I would like to see happen is to have your son contact me and meet me at the same gas station to return the sub promptly without me having to come to your house (I then read her her address over the phone). She said she would have her husband contact me and I told her that would be perfectly fine and acceptable.
Her husband called, and he was just like me, calm, nice, not at all concerned and made arrangements to meet me, took the sub, apologized for his son who was off at college and apologized for his wife not calling sooner or telling him. We shook hand and departed neither party angry, no hard feelings.
Thats been the only time and I've learned my lesson and am cautious now.