The last straw for me was when they blocked a transaction of a few hundred dollars without any explaination. I was talking to a support rep for well over an hour, repeatedly being told that there is no security team at PayPal that can see why a transaction was blocked override the block. I was told the security system was a black box, they wouldn't transferred me to a supervisor, and the end result was a recommendation to try a different payment system like bank transfer.
This happened to be on the day we were selling our house. The buyer came in with a cash offer and a 7-day close. The inspection results came back after the paperwork was already drawn up, when they asked for a few hundred for electrical repairs it should have been easier to do that as an addendum rather that completely redoing the closing settlement sheet. I guess PayPal had better ideas.