Should you include negative keywords?
YES! And here's a few reasons why...
There are many reasons why your keyword strategy should include negative keywords because negative keywords let advertising platforms such as Google Ads know that you wish to filter our specific search terms because they are not relevant to the products or services you offer.
Say you have an online clothing store that sells motorbike clothing but you have made a business decision to NOT sell motorbike helmets. 'Helmets' in this instance would be a vital negative keyword to include in your strategy to ensure users are not clicking on your Search ads (that cost your advertising budget) and expect to see helmets in your catalog.
Fewer impressions = increased CTR
If you are filtering out searches with your negative keywords and maintaining clicks you'll see your CTR improve however it may be the case that a newly added negative keyword can cause your campaign impressions and clicks to drop suddenly...this means your negative keyword has had an adverse effect and filtered out way too much traffic.
So it's important to really understand keyword match types and how they work in parallel. Negative keywords can have the same board, phase, and exact match types applied to them which will essentially apply stronger filters depending on the keywords you have included in your campaigns.
Higher quality clicks
If you apply an effective keyword strategy your clicks should be of a higher quality and therefore provide your business with a stronger opportunity to convert the desired business goals.
Don't let your advertising platform assume anything!
Platforms such as Google Ads often assume if you sell A and B, AB must be relevant to your business as well. If AB isn't relevant at all, AB becomes a very valuable negative keyword to include in your campaign to ensure your campaign ROI continue to be maximized and you are not wasting clicks and budget when Google (for example) take it upon themselves to present your ad to a user looking for AB.