Files show up despite being excluded from Search

Question

I recently got the request to exclude 2 terms from returning any search results within our SharePoint 2013 farm - let's call them TermA and TermB. What I did was to add "-TermA -TermB" to the search results page's default query.

This all worked fine for TermA but when searching for TermB I now get a PowerPoint result block with files that should be excluded (refiners are empty and there are no other files displayed):

When clicking on 'Show more' the site basically refreshes to this:

http://intranet.com/search/Pages/results.aspx#__=%7B%22k%22%3A%22TermB%22%2C%22o%22%3Anull%2C%22s%22%3A0%2C%22r%22%3A%5B%7B%22n%22%3A%22FileType%22%2C%22t%22%3A%5B%22equals%28%5C%22odp%5C%22%29%22%2C%22equals%28%5C%22ppt%5C%22%29%22%2C%22equals%28%5C%22pptm%5C%22%29%22%2C%22equals%28%5C%22pptx%5C%22%29%22%2C%22equals%28%5C%22potm%5C%22%29%22%2C%22equals%28%5C%22potx%5C%22%29%22%2C%22equals%28%5C%22ppam%5C%22%29%22%2C%22equals%28%5C%22ppsm%5C%22%29%22%2C%22equals%28%5C%22ppsx%5C%22%29%22%5D%2C%22o%22%3A%22or%22%2C%22k%22%3Afalse%2C%22m%22%3Anull%7D%5D%2C%22l%22%3A0%2C%22m%22%3A%22%22%2C%22d%22%3A0%2C%22x%22%3Anull%2C%22e%22%3A%2D1%7D

My questions are:

• Why does the result block still show up and how do I disable it (without setting the PowerPoint Query Rule to inactive)?
• Is there a better way to remove specific terms from Search since my approach only deals with the one Results page (maybe Crawl Rules?)