In your (frankly terrifying) example, would the site have had to have ranked for "naked bieber pics", showing up in the results and then you click it to pull the search terms? Because that would seem to be pretty innocuous.
There's been various HN posts about how people circumvent browser privacy settings to track you across websites and even tricks such as generating an almost unique key by hashing together browser, fonts installed, IP address, etc.. I'm not sure of the current state of play in that war though.
I guess if you really don't want people to track private searches with your accounts, use a whole other browser where you're not logged into Google in incognito mode.
Edit: judging by the downvotes, I guess a good bunch of hackers like to live in atrocity!
Many people omit the word, "temporary". The suspicious part of me says they do it so their (mis-quoted) statement appears more bold and uncompromising.
Duck duck go actually redirects you in a way so that the referrer is not known to the site. They all think you came from duckduckgo.com. DDG also keeps no logs. Basically your own activity online cannot be used against you.
Now, privacy aside, I really like DDG for other reasons, like search relevance, continuous scrolling, zero-click info, etc. So its kind of win-win for me.