Many times, people add negative keyword phrases to Google Ads. For example, if a store only sells fiber optic networking devices, they might add the negative keyword: “ethernet networks”.
However, this keyword would not prevent the ad from showing up on the keyword phrase search: “ethernet solutions”. That is because solutions is not in the negative keyword phrase: “ethernet networks”. A better strategy is to use the negative keyword: “ethernet” alone.
That will eliminate all keyword phrases with the word ethernet in it. The one disadvantage is that if people searched on “Ethernet vs Fiber Optic Networks” our ad would not show.
Picture of one word negative vs. two word negative on Google Ads. We used the single word maps because we didn't want any maps to show. Market research we did as two words because market and research were both good keywords for our client. Just "market research" together wasn't a relevant keyword.
However, this may be worth the tradeoff for two reasons:
1. There may be many less instances where our ad will not show when we want it to vs. instances where our ad shows when we do not want it to
2. The Ethernet vs Fiber optic keywords are lower down on the sales funnel and therefore not that valuable to us
Bottom line, when adding negative keywords to Google and Microsoft Ad campaigns use one word keywords whenever it’s possible.