I nearly got scammed by some Nigerians (Im sure not all Nigerians behave like this but there are a disgraceful group). Nigerians particularly like DIAMOND rings. Often creating a very long story about a partner who is a missionary and has to travel immedialty to Nigeria and could you ship the items for the said partners birthday. Sounds plausible but it is a scam. Dont fall for it and dont send the goods.
I once had to relist a Diamond Ring 3 times and every time it was listed with 'Buy it Now' one of the Nigerians clicked on it within a day and the scam started all over again. Usually you can spot these as they have no feedback scores or have a feedback score of 1. To prevent this when listing your item click the box that prevents anyone with less than 5 feedback scores from bidding on your item. This is not fool proof and sometimes people still get through.
Thankfully I sold the ring by removing it for sale from international buyers.
My partner nearly got scammmed with a car and the seller offered an amazing below book asking price if we could pick it up from a port in the UK for import from Portugal. Some story about registration laws and the grey market. We strangely spotted that this had happened to many other people by putting in a google search as something didnt add up. Dont pick up from any port as when you get there I gurantee the car wont be there and neither will the money youve paid the buyer with a bank draft or other means of UK cleared payment.
Hope this is of some help.
The previous person advised to check for fake emails and bad spelling. This is particularly relevant when it comes to paypal addresses. The differences are not huge between the fake emails but paypal have a standard and never have spelling errors.
Good look and heres to getting rid of scammers and maintaining a great eBay trading environment (apologies for any spelling mistakes I may have made in this little rant of mine!)