How to disable Search to index content inside documents

Have you ever had a requirement from a client to customize SharePoint Search, to disallow users from querying for any content inside documents?
I had this request recently, and it was a while until I found solution for it..

To accomplish this, I had to remove some internal Crawled properties from the Search Service Application.
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Check this link: http://www.itidea.nl/index.php/how-to-delete-crawled-properties.

Other possible ways to accomplish this, depending on the scenario:
  1) Create noise keywords, to avoid Search from indexing specific keywords
  2) Remove the file extensions from the "File Types" section of Search. This will prevent Search from performing any crawl actions on those file extensions. No search results will be shown for files not included in the "File Types" section.
  3) Uninstall the specific iFilters used for Crawling the documents (might not be practical if you have different requirements for Search in the Farm)
  4) Delete any particular Managed Properties that you do not want to query for/display in the search results.
  5) Remove permissions from the Search Crawl account