Just to provide an update here for other advertisers learning about this - I've been officially told THIS IS THE INTENDED functionality for Bing and that I just need to add negative keywords. I find this to be a very bad choice for Bing, it almost seems
like a very misguided way to try to differentiate themselves from AdWords at their customers' expense (and their profit).
The worst case I found of it was close variation terms being used for branded keywords that were exact match only. So my brand term is [usa military medals] and I'm seeing impressions and clicks for the query american military medals. Bing is automatically
un-branding my terms for me.
That seems absolutely ridiculous. Any advertiser can easily set up broad match or broad match modifier keywords on their account if their aim is to trigger synonyms or similar terms for further refining. When you apply this same logic to phrase and exact
you are leaving customers with no options to finely tune their keywords FROM THE START. Instead what happens is customers WASTE MONEY for clicks that they did not want. They have to wait for those waste clicks to come through and THEN apply negative keywords
post wasted spend. What a way to inspire confidence in your service.
For reference this is what AdWords says about close variations and what I had believed was also Bing's policy as it seems much more efficient and logical:
"So that you don't miss out on potential customers, we'll show your ads for close variations of your phrase and exact match keywords to maximize the potential for your ads to show on relevant searches. Close variations include misspellings, singular forms, plural forms, acronyms, stemmings (such as floor and flooring), abbreviations, and accents. So there's no need to separately add close variations as keywords.
For example, if your phrase match keyword is "kid's scooter," you'd still want to show your ad when someone searches for "kids scooter" or "kid scooters."
Keep in mind that even though we show close variations of your phrase and exact match keywords, these match types still give you more control than broad match. That's because broad match keywords also show for synonyms and related searches, which aren't considered close variations."https://support.google.com/adwords/answer/2497836?hl=en