There have been times I had a buyer try to pay me after a week's time had passed. Some buyers feel they can just pay when they want to. In my auction I state payment must be made within 2 days or I can offer it to my under bidder. They paid me with pay pal a week later, and I returned their payment (I made the sale with the under bidder). I am quite strict with my auctions, while I only sell authentic goods and ship quickly, I refuse to be stuck "holding the bag" waiting for a buyer who will pay when they feel like it. And some people just have excuse after excuse, they waste your time. So I just move on.
If more sellers were strict about payment, these lazy buyers would pay right away. I don't mind to wait for a payment if a buyer has communicated with me about it. I have waited for payment from many wonderful buyers, but communication was key. I refuse to just sit tight and wait and see if the winning bidder will pay, if they don't pay right away (my 2 day limit) and they have not emailed me about it, forget it. I'm not hard up to make a sale, so I refuse to be at their mercy.