Buyer pays for via paypal some water based lubricant. After around 7 days he messages us to say he hasn't received the item and wants a refund.

We are always very suspicious of people wanting refund rather than replacements because it just stinks that they actually have the item and just want their money back.

After some persuasion the buyer agrees that we send a replacement. However, 7 days later he says he hasn't got the replacement and opens up an item not received case via eBay.

eBay refund him in full and this buyer now has 2 items for free. He then leaves negative feedback!