Significance of Bing's enboldening of some search results

Question

What's the significance of Bing's enboldening in some search result entries?

I have found no answer to this from web search using Google... or Bing :)

For example, some words in some entries (inc. different words in identical phrases):

http://www.bing.com/search?q=London&q1=site%3Ahttp%3A%2F%2Fwww.chrisjj.com%2Ftango%2Fcjjsets%2F

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Answer 1

Looks like a bug due to bungled highlighting of term matches.

A simpler case:

http://www.bing.com/search?q=Carablanca+falta+Chris

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Bad highlighting on results: https://i.sstatic.net/xltFy.png (bold)

Bad highlighting on cached page: https://i.sstatic.net/WByOR.png (red)