I've only had one bad experience on here.

I worked out a deal to take time off to meet with someone and inspect/purchase what they were selling the next day. I had offered to buy the item that night if they got back to me in time to get to the bank before they closed but the seller contacted me about 15 minutes after 6 PM so no dice there (amount was too much for my daily ATM withdraw limit). I get off work after using PTO on short notice only to have the guy say "Sorry, sold it last night". He didn't think that should require a phone call. Now it was a great deal on a gun and I was bummed I wasn't going to be getting it. But I was absolutely pissed that I put my neck on the line at work asking for half the day off on extremely short notice for something to most managers wouldn't be worthy of leaving work.

To me, that's totally unacceptable.