DDG only just recently added the feature that they show you which terms they ignored… most of the time. This is actually my main problem with DDG (which is my default search engine), that they like to ignore even quotation mark-forced words. My impression is that Google sees "" as an important signal for what you want while DDG sees it as something you probably did by mistake and decides to show you a ton of unrelated results (with the word not even showing up at all), even on the first page. It’s the one thing that annoys me about the otherwise superior search of DDG.