Oh, I've got a really good one...
Years ago, back when parts for XY color Atari monitors were not readily available, I had found an operator who had AT LEAST 5 complete and working Atari vector monitors that were sitting on the shelf and pulled from the various games still working. They told me that they would be sitting there, waiting for me, and whenever i needed one, they would let me have them for $50 each. Since they assured me that they wouldn't sell them to anyone else, i figured that they would be there for me whenever i needed them.
My MISTAKE is that i told a fellow collector about them, but didn't tell him WHO had them, just what (Large) city they were in. He did some digging (without me knowing about it) and went there (a three hour drive) and picked up EVERY SINGLE complete monitor and ONLY left partial units or parts. Fast forward a little while. I need to fix either my Space Dual or Tempest (i forget which), so i call them up. He seems quite confused about why i am calling. He then tells me that my "friend" had already come down to pick them all up. I was like "what do you mean? You told me that you were holding them for me!". I bet you can guess his response...
"He indicated to us that he was picking them up on your behalf. As if he was getting them for YOU!"
Needless to say, I lost all faith in humanity that day. i hope that there is a special place in Hell for people like that guy...