Broad matching keywords is a popular strategy for B2B and B2C search marketers.  It allows you to cast a wide net and maximize your long-tail keyword catch.  But without thorough negative keyword research, the broad match strategy can trigger your ad for some way-out-of-left-field searches. This inflates your ad impressions and dilutes your click through rate (or attracts non-converting clicks), which impacts your overall campaign performance and spend.  

How Negative Keyword Search Is Typically Performed

There are several “traditional” ways you can build up your negative keyword list:

• Keyword research tools - like Google’s Keyword Tool, Wordtracker, SpyFu, or Keyword Discovery
• Search engines – scan search engine result pages to find irrelevant words
• Competitors’ websites -  similar sites might carry brands or accessories that you don’t, or offer different but related services
• Site search logs – if site visitors are searching for things on your site you don’t carry, they’re also searching in the major engines
• Web analytics – check your keyword referrals to weed out irrelevant search queries

The problem with keyword research tools is that often long tail keyword searches don't happen frequently enough to get picked up by even the priciest of keyword research tools. And we know from Chris Anderson's The Long Tail that all these little searches add up.

And you won't see referral keywords in your web analytics if nobody clicks your ad. (Yes, customers may not know what CRM software is for, but they know it's not a curling iron!)  You need another way to anticipate irrelevant search queries.

Using eBay for Negative Keyword Research

The "world’s largest garage sale" also houses a vast collection of long-tail keywords. Any search marketer can discover long-tail negative keywords for broad match terms.

For example, “Maximizer” is the name of a popular CRM software, but the term is also used in branding for a wide range of other products, including curling irons, vitamins, indoor tanning lotion, audio plug-ins, pool cues, and even “male enhancement” products.  There are a few advertisers competing in the software space that are appearing for these other products:

Results for "maximizer curling iron"

Results for "tan maximizer" 

This indicates that the CRM advertisers are broad matching “maximizer.” Even though quality score, in theory, should reward the actual sellers of these products for high keyword-to-landing page relevance, the software ads outrank them.  (This is most likely due to high maximum bids, but it could also be happening because etailers are not setting the proper landing pages for specific product keywords and are just sending clicks to the home page, which is happening with some of the tanning lotion sites.) A simple search for "Maximizer" in eBay delivers over 250 results...

...and many of them don't even appear in Google's keyword research tool:

eBay is another (free) tool you can add to your SEM arsenal, and it could help you improve your overall campaign performance - raising click through rates, improving your ad positions, and lowering your average cost per click - making you look like a hero.