Well there are strange cases when we talked with a friend about something and then suddenly the algorithm decided to push content or ads that are related to the topic. While we didn't search stuff on the topic.
Yeah, saying "some people" believe they experience this is an understatement. People my age seem to generally be aware their phones send them targeted ads based on their conversations. It happened to me frequently with my Nexus in the Google News app. Happens to my girlfriend on her Android in the Facebook app. I switched to iPhone, never installed Facebook, and haven't seen the same effect in Apple's news app.
