Realistically, I think most of the time, if the ad is targeted well, there are no issues. I see a good amount of ads, and the most annoying ones, to me, are the most poorly targeted ones.

However, I do think there is an inherent creepiness involved in the amount of tracking involved to achieve that level of targeting. Normally, as a person who is not terribly privacy minded, I'm not thinking about this tracking that watches everything I do. That is, until I had an experience like the top comment. I ripped the mic out of my Amazon FireTV remote that day. It made me uncomfortable that my conversation left the room without my knowledge or consent. (I realize this was Amazon, not Google, but they all do this sort of thing.)

Edit: I think ad targeting has to achieve a delicate balance of serving potentially helpful ads, while not alerting the target that they are part of the Matrix.