They charge my credit card two months after the purchase, but refund at the same moment the seller refunds.
It's impossible to keep track - sometimes I get a refund two months before I get charged for the deal... :/
(plus - I hate this spam-filter-question thing, why do I need to enter it almost every time I post? Why is it still used for legitimate users with hundreds of posts? At least add a picture of a naked woman to make it interesting...)
I just keep a balance in my PayPal account. Then I transfer money to PayPal when it gets empty.
The spam filter is a work in progress. However it seems to be effective.
If PayPal charges your card two months after you paid, it means that the seller just got round to doing the transaction. Paypal transactions are automatic to your CC and Bank, so blame the lame sellers that you are dealing with.
If they put a naked woman on there, you would bitch about it being the wrong woman.
Just playin with ya.
That spam filter will get old to lots of people soon.
I know many a firm that would love to be in your position. 
I think it has to do with how my credit card company manages international transactions.
There is a delay of at least a month between an international charge on the credit card and the time the amount is deducted from my bank account. Maybe PayPal delays this info, maybe it's my credit card company. So for March I was charged for international transactions I made during January (and local transactions from February). However, somehow money that enters my credit card bill is immediately deducted from this month's sum, so I saw refunds from the end of February alongside charges from January.
But if for example I make a purchase and get refunded a few days later (e.g. out of stock), the refund may appear immediately in my credit card bill but the payment can be delayed till next month's bill.
So I was wrong about the two months, but I definitely remember seeing refunds a month before their respective payments appeared.
Strange.