Let us remember the age-old teaching: the man who is dishonest in small things will also be dishonest in larger matters.
Free Avast installed Bing as my search engine, replacing Google. Bing, for me, is a substantially inferior product; it simply doesn't produce enough meaningful or relevant answers to my search enquiries.
Here's the thing. Regardless of Avast's opinion about the security merits or demerits of Bing, Avast installed an unwelcome guest without my permission. Moreover, Avast left no easy way to uninstall Bing.
By their fruits, you shall know them.