Taking money out of your Pay-Pal account, and not having a balance, will not
in any way stop Pay-Pal if they decide to "take" money from your account.
In order to have a Pay-Pal account, you must give Pay-Pal the right to take
money either from your credit card or your bank account (and usually you are
pressured to make both available). If there is a "chargeback", this gives
them the legal right -- enforceable in court if necessary -- to take that
money from you via either the credit card or the bank account, even if it's
months later and you no longer have a Pay-Pal balance. And, if the credit
card and checking accounts in question are closed, to collect it in the same
manner as any other alleged debt through a legal action.
That said, I have had problems with Pay-Pal transactions, and so have people
who I know (one whose entire account was "stolen" to the tune of thousands
of dollars), and, in the end, after some hassle and some time, it was all
resolved "satisfactorily".