I have a buddy who proved to his IT colleagues that DuckDuckGo does not protect your privacy at any level that would inspire confidence. One of the guys he worked with was having a flame war with his ex wife over the custody of their two children.
The guy posted nasty, defamatory comments at various online bulletin boards, etc. His intent was to win his kids back by making her look like an unfit mother. He used DuckDuckGo typing in search strings that included the phrase non legal ways to get your kids back from your wife. (or words to that effect)
He had apparently tried legal ways to regain partial custody of his girl and boy that resulted only in expensive attorney fees. My IT buddy would not tell me how he knew all of this, but said that the cache of DuckDuckGo search strings is not hard to access if you work there or know somebody who works there. As far as I can tell hackers have not had any luck compromising the security walls there, but its the insiders that have access to things that any DuckDuckGo user would be quite alarmed to know about.
I know the above sounds a little fuzzy, but here is what I do know. The guy who was having the custody battle had his ISP subpoenaed and he was prosecuted for libel or defamation of character(maybe both). He was also charge with something like endangering the caregiver of his children.(Can not remember the legal terminology for this) He says that he only used DuckDuckGo(He NEVER used Google, Yahoo, Bing, etc) to search for ways to get his kid back knowing that the nature of his searches could potentially incriminate.
I am relived to know that no search engine is above the law and that true web surfing anonymity is illusive if not impossible. Also, I would like to know more about how user privacy is protected by avoiding a filter bubble of personalized search results?
I wish their founder, Gabriel Weinberg, would make that more transparent, but I understand he is in a very proprietary business.