I was struggeling with the search returning to much result when users wrote for example Episerver and SharePoint since 98% of the result was on the word "and".
After contact with support I learned that Episerver has choose to disable the elastic search feature stopwords (https://www.elastic.co/guide/en/elasticsearch/guide/current/stopwords.html) by default so all words are included in the index.
There exist a stopword function in the framework (http://world.episerver.com/documentation/Class-library/?documentId=find/8/7C04D56A) but that one can only be used for MoreLikeThis-query and I would like to be able to do that for all kinds of query, both unified one and typed one.