If memory serves me right, at one point in search history, AdWords Dynamic Keyword Insertion (DKI) was used to insert a user’s query into your ad copy. Whether or not that was the case in the past is now irrelevant because Google’s documentation is clear that DKI only inserts keywords from the same ad group.
This is a big distinction that many bloggers continue to miss as recently as December 2014 by either carelessly interchanging “query” and “keyword” or by forgetting to update their research when describing DKI.
Why does it matter that DKI has nothing to do with queries? Well, since it’s only inserting keywords from that ad group, the “con” of crazy broad matching and ending up with ad copy as horrible as “Save on Leg Amputees” (as PPC Hero called out way back in 2009) is now completely within the advertiser’s control. This ad copy would only be possible if the advertiser was bidding on the keyword “leg amputees” within that ad group, not if the query “leg amputees” matched to “leg prosthesis.” One possible solution is to isolate keywords that are safe or make grammatical sense when being inserted from those that are not and only use DKI in pre-checked “safe” ad groups.
Better still, avoid DKI completely and use single-keyword ad groups.