You nailed it. I've had personalized ads disabled for years, and a few years back I switched it back on to see if it's any better.

At the time I was shopping for a Pebble smartwatch and kept checking the site if it's on sale, because Pebble had a tendency to do short-time discounts without actually announcing them. After a few times, almost every Google ad was for "Pebble Smartwatch". It not only wasn't useful, it was annoying.