Targeted ads are basically homeopathic medicine in a different market:
They take a small group of people with money who don't care about the shit you sell and honestly resent seeing your beef jerky ad when trying to buy a couch, dilute it with a bunch of people who once Googled "beef jerky" to figure out that one brand or make a funny meme so as to neutralize statistical qualities about the cohort you might not like, and pretend it'll do something for your business besides act like a sinkhole for your money.
But I've slowly come to think most business statistics are deeply flawed, but now we're trapped using them because there was an upward slope to the cliff and people are dumb. Even if you point out that their flawed number models caused their businesses to collapse over and over for no reason but poor optimization, most people just hear "made money for a while".
Targeted ads are a joke in 2017.
Notification abuse is honestly worse. It is mostly stupid notifications that were clearly not written by someone with any advertising experience.