Sellers are learning how to ‘hack’ BestMatch – is this really good for eBay Buyers?

April 10, 2008

Marketplaces ChannelAdvisor By ChannelAdvisor

Outside of the World of eBay in the wonderful world of the Internet, google’s algorithmic search engine is constantly being gamed by those with good intentions (white hat), unknown intentions (grey hats) and devious intentions (black hats).  This is broadly known as search engine optimization or SEO.  Google and the bad guys are locked in a never-ending arms race where google works constantly to stay one step ahead of linkfarms, cloning, cloaking, linkspam and a whole dictionary of strategies designed to confuse the google bots and increase a website’s organic traffic.

Back in our eBay World, as you probably already know in March, eBay switched the search engine from a reverse chronological (aka ‘ending first’) system to a black box algorithm known as BestMatch.  BestMatch has many positive aspects and seems to be working as we’ve noted.

However, it only took about a month, but now we’re hearing from sellers that are upset that other sellers are significantly gaming the system.  I received a great example of this from a long-time reader and video game seller today that blew me away.

Here’s the example of the term “nintendo wii” with BestMatch results.  I’ve numbered the top 6 results for us to discuss (you may need to click on the below to see the details):


What do you notice about results 1, 2 and 6?  Well, let’s just say these are very new systems.  Why on earth would a seller put the word new into a title 5-10 times and use that valuable space on a repeated word instead of something like “includes 5 controllers and 4 games”?

Yep, you guessed, it, doing so appears to increase your BestMatch score significantly.  Let’s assume that these sellers have simliar performance histories as they all have around 300 feedback and that’s a level that’s hard to mess up.

Now look at the prices and the ending times – two other heavily weighted bestmatch inputs.  Item 2 ends in 13 minutes (the longest time in these 6), yet is rated second. It’s price is clearly higher than item 5.

So if it isn’t performance or price or time, then why would item 2 be ranked above the less expensive, more temporal listings 4 and 5?

It must be the title!  By including a whopping 12 NEWs in the title this seller has been able to get much more exposure for the item and has cleverly filled in the missing title information occupied by all those NEWS in a subtitle.

In the world of computer science we call this ability to take advantage of an unforeseen/anticipated aspect of an algorithm a hack.  Now we are officially seeing the kick off of what I think will be a long and arduous (sometimes very profitable) saga of BestMatch hacks.

How can YOU hack BestMatch to your advantage
The best thing about this is eBay has given us the tools to hack BestMatch.  In their research lab area, as we’ve mentioned before they have a very simple utility called the Bayestimator.

Here’s how to leverage this tool:

Step 1:  Enter in your boring old original descriptive title that a buyer would understand and get your scores (here we’ve tested “New nintendo wii includes controller and 5 games:


Overall this title earns a 40% score and the words that eBay likes are: “new 5 and games”
eBay gives zero juice to nintendo, wii, and so those are somewhat wasted words in the world of BestMatch.

Now that we know new is popular let’s try a new title, let’s say something like: “nintendo wii console new new new new new new” (ok i controlled myself to 6 ‘news’).


How about that we went from an overall score of 40% to a 100% – eBay’s BM algo loves this new title and in fact I have 11 more characters available.  Guess which word would be best there?

White hat, grey hat, or black hat?
As far as know, aside from being a) annoying to look at+read and b) highly repetitive, these titles don’t violate any eBay policies so I think that automatically would classify this kind of gaming as grey hat.

The BestMatch race begins, can you afford not to play?
I’m sure eBay has already noticed this and is working on ways for BM to be smart enough to actually discount the repetitive use of potentially high scoring words (just like google does when you spam the heck out of metatags).  But, by the time they roll that, sellers will be on to the next hack and so the game continues.  Here’s how it’s different.  In the google world, you may have one or two results pop in above those that are more relevant so it’s a minor annoyance but doesn’t really impact anyone that negatively.  Also on google you can always use adwords to get your message out there.

What’s tough with these eBay BM hacks is that many sellers are going to feel economic pressure to rip off the white hat and put on a grey hat.  What if one day you notice your top selling item’s conversion rates are dropping?  You do some searches on eBay and realise all of your hard work on DSRs, title optimization, great pictures and low prices are being nullified by someone doing some BM hacks.  You can report them to eBay and they will ultimately fix it, but in the interim, your only strategy is really a ‘if you can’t beat them join them’ approach.

What about the buyers?
Well, I think we can all agree that the results for ‘nintendo wii’ with the BM hacks have actually become much lower in quality than in the ‘ending first’ world (you can’t hack time), so it will be interesting to see what kind of hack-curve eBay faces here and how fast can they get to a BM 3.0 /4.0 that eliminates these kinds of things and truly offers a long-term better buyer experience.

Report your BestMatch hacks.
Have you seen/utilised any BM hacks? Do you feel pressure to go grey hat?  If so, let me know.  While this is a new (new new new new new new new!) eBay issue, I’m sure we haven’t seen the last of it.