Negatives are important because they eliminate unqualified traffic from seeing and possibly clicking on your ads which in turn helps you cut down on wasted spend.
I remember one client who was selling an air purification product that – I can’t remember the exact brand name – but the model name/number included something like 15-X. When I first started managing the account, which had been running for quite some time, I noticed that this ad group had a huge number of impressions and quite a few clicks but very few conversions and those at an astronomically high CPA. I reviewed the search query report for the previous six months and saw the majority of searches were for ….adult material. If memory serves me well we were talking literally thousands of dollars in wasted spend. Since that day I have made reviewing the search query report a regular exercise for every account I manage.
Great sources for negative keywords are the aforementioned search query report as well the dimensions>search terms report. These tend to show the same keywords but I have found search terms in the dimension report that were not in the search query report so it can pay to review both. Also if you are managing a Shopping campaign which does not use keywords, there is no search query report and so you have to use the dimensions report.
I’ve also found great negative keywords in the suggested keywords function as well as Keyword Planner. This is in addition to the usual suspects such as “free”, “demo” and similar (unless of course your offer involves a “free demo”).
Another source is the client’s site search if they can provide a spreadsheet that shows all search terms used on the site.
If you have ever used the search query report to exclude keywords you know that the default is exact match. What this means is – if any one types in that
exact search phrase – your ads will not trigger. So if someone searches for dog bones using that exact phrase and you have [dog bones] as your negative,
then your ad will not trigger.
However is someone uses the search query “where can i buy dog bones” – your ad would trigger. Here we can filter out these types of queries by using “phrase match” – so for example if we have “dog bones” as one of our negatives, any search query that includes “dog bones” intact will not trigger your ads.
Finally there is broad match where in this case you could use the term “dog bone” or add as two separate negatives “dog” and “bone” or even use all three.
As clicks become ever more expensive you simply cannot afford not to use negatives.