I usually get the annoying lazy ass twats when I wanna buy something, like you say when you're about to do a deal they vanish and are hard to track down, or even worse with what iv'e had several times is completing the deal and sending the money over, to then get the slowest and worst customer service on the planet where it takes over 1 month for the item to arrive, and takes them a week to reply to a simple message.
I also hate the ones where they agree on a deal so you respond and say "yes lets do this" then they don't respond for several days and you have to do their job for them and keep reminding them to get things done lol. HATE those ones!
Some people really amaze me, it makes me wonder do they really
want to sell this thing they're selling??, this ebay seller from 2 months ago angered me a bit, I sent a message saying "is there any paint missing or damage on the reverse?".. to get the reply saying "i'll let you know tomorrow when I get time to look at it", got no response for 2 days so I asked again, then waited another
day for a response saying "i'll let you know tonight when i'm home", didn't get a reply so I contacted again the next day asking if he has looked at it yet, then he replied 1 day later saying "sorry I don't have time cus of the missus, kids and the dog and that".......
Then the auction ended and the lazy prick lost out on an extra bidder!