You have probably traded with a reputable trader that had no interest to do a chargeback on you. It's different when you have unknown people buying bitcoins for Paypal.
Even birds on the trees know until now that PayPal should be absolutely avoided. I would trust a Paypal transaction only if I know where the guy lives that I trade with and I know him personally. But in this situation, I wouldn't even need PayPal to do a trade!
The essential is to stay away from PayPal!
It's against their TOS so it has nothing to do with trusting people..
If they catch you kiss your account + money buy.
And this could also be delayed..
You do trades then later you wind up in trouble after the fact.
It's against their TOS ..i think i need to keep repeating that