Recently I experienced some of the dreaded slaps by PayPal. They limited my account for over two weeks, disrupting my business, based on a simple purchase that I made. Neither I, nor the seller, disputed anything having to do with this transaction yet PP decided, in their great wisdom, to review it. All of my entreaties lead to only 'canned replies' by PayPal, if anything.
Then, after the account was mysteriously restored (not sure why).
I thought it was all over.
Yet a couple of days ago a recurring payment went through that actually should have been canceled. I contacted that company and asked that they please refund the money. They immediately said OK and put the refund through. PayPal, however, decided to put a temporary hold on that transaction.
For years I've been hearing fellow Webmasters say to watch out for PayPal but I never got 'slapped' myself (despite HEAVY usage of PayPal).
Some tips if you use PayPal for your business:
Have a separate account for personal purchases or purchases that you worry may trigger a review.
Make sure your phone number is up to date.
Anything else?