Yeah, this one is really annoying. Especially because I already have the item I wanted so what good does it do to advertise something I already purchased?
These advertising algorithms also caused me some issues over a video game. It was a brand new game that I had never heard of but was on sale for a really deep discount on release. It looked potentially very interesting and was very tempted to just buy it, but instead decided to be prudent and look for online reviews first. The name of the game is SOMA, which I searched and found various written and video game reviews. After going through numerous sites I decided that it looked like a great game but it features certain gameplay mechanics with I don't like. So I decided against buying it for myself and went on with my life as normal. Except that for some strange reason every website I visited kept popping up advertising featuring barely clothed women. My wife took notice and joked "what kind of articles are you really reading?" It turns out that there is a lingerie store also called Soma. I took a good 5-6 months before those lingerie ads stopped appearing.