@tennoseremel At this point usefulness of the ad to you as an individual user may not really be relevant.

And you rarely can "just" continue doing whatever you do, the prices grow, the complexity of what you do rises over time, even if you're just a news site, for example.

Also, the line between "user data mining ads" and "content relevant ads" blurs significantly if the content in your service is user-centric, doesn't it.

There's no easy answers here. There's no disco solution. It wouldn't be much of a problem if there were, would it.