The trick relies on one small fact: People often make spelling mistakes on eBay. A missed typo can turn a high-profile item likely to draw plenty of bids into a vacant listing that no one stumbles upon.
That's where FatFingers comes in, a website designed to help you search for these typo-ridden auctions.
Here's how it works:
Once you head over to FatFingers, you can select which country you're in. Then just type in the item you're looking for. FatFingers recommends using only one keyword if you can, so it's best to usually just go with the brand name.
Here, for example, we searched for Sennheiser, a popular brand of high-quality headphones (and prone to misspelling).

FatFingers.com
Once you've inputted the brand of whatever you're looking for, click "Find" and then the "Click to view on eBay" button and you'll be whisked off to the bidding site, where FatFingers has already searched for plenty of spelling variations.

eBay
While it's not always guaranteed you'll find an auction that hasn't been spotted, it's a great strategy for finding a good deal if you're patient.
You can try to find a misspelled auction of your own by heading over to FatFingers.