eBay is a place where lots of currency is transferred worldwide, every day of the year. It can easily be transferred online instantly (through PayPal) - right across the globe. This is brilliant. Buyers pay quick and recieve thier item fast and sellers get their money quicker than ever before. But of course, with money everywhere, and people looking to spend/earn it, there is an open window for scamming.
Google Defines a scam as "A ploy by a shyster to raise money" and in this guide I aim to show you how to recognize and stop these shysters from operating.
Part 1: Recognizing Fraud/Scams
Scams usually come across in a simple email. This will either be from a person who openly wishes to defraud you of your money, or a person with the same aim, who impersonates eBay/Paypal to do this. Recognizing the second of these is simple, as explained many times in eBay, ALL ebay related emails/website addresses end in "ebay.<area>" for example: ebay.com, ebay.co.uk, ebay.ie, ebay.au. And of course, if you are unsure whether an email/website is eBay or an impersonation, you can always download the eBay Toolbar, which has built in protection against most scams, and will tell you when to avoid a site.
Avoiding people who want your money, but aren't impersonating eBay/PayPal is alot harder, unless you know what your doing. First of all, I reccomend considering setting some Buyer Requirements, which will stop people of a certain type (for example, people with no feedback, or people without PayPal) actually bidding on your items. Remember, most scammers don't actually have a PayPal account, as this would help them be tracked down.
When using Buy-It-Now, simply make sure "require instant payment" is enabled, and that way the listing is only considered "bought" when the buyer has actually paid, and until then is still available to others.
The most common scam you will hear of is the "I must buy this now for my (boyfriend/mother/dog) who lives in Nigeria is having a birthday party and it must get to them" - and upon letting them buy it you will recieve fake emails saying the Payment is on it's way etc. and that you should send the item, which results in you having no item, and no money. THIS IS EASILY AVOIDABLE! If you should get asked to end an auction early for a nigerian, simply add them to your Blocked Buyers/Bidders List and they won't be able to bid. Should the user create a new account and win your item using that, read part 2 of this guide.
Part 2: Reporting the scam/fraud
So, you've been scammed. Reporting this is easy, simply follow these 3 easy steps:
Report the buyer by clicking into the Contact Us section of eBay and selecting "Problems with other members"
If you believe the buyer has registered with/provided you with false contact information (such as a fake address) report in the Reporting False Identities help section aswell.
Wait until they are suspended from eBay (you will receive an email telling you that the appropriate action against the buyer has been taken, and the buyer will have "This user is no longer registered with eBay" on their member profile) - and, once they are suspended you can create and close an Unpaid Item Dispute immeadiatley, which will reclaim your seller fees.
If, however you have sent the scammer/buyer your item, this will prove hard to recover, as without physical force it is unlikley anyone can retrieve your item.
If you have sent your buyer money this is easy to reclaim. If the money was sent through paypal, simply visit the PayPal website, log in and go into the "resolution centre" where you can claim back recently sent money from a buyer. If the money was sent via a bank transfer/cheque, call your bank and ask for the payment to be stopped/refunded. If you posted your money as cash then, as with the item situatuation, this will be very hard to retrieve.
If in doubt about whether or not something is a scam, check your eBay toolbar, contact eBay or discuss it in the community. There is a helpful topic about the nigerian scammers available here, where all your related questions can be answered.