I'm right there with you on retargeting. It's been my experience that this is smoke and mirrors and something that a client can sell to their bosses because it sounds like it would work.

If a campaign isn't working, I talk to our client about it and if I think I can fix it, I'm open about that too. It's easy to spend tens of thousands of dollars on useless ad spend optimized for the wrong things, and it's unfortunately the responsibility of the advertiser at this point to show their client what metrics actually matter, how to track them, and to give the client the ability to check in whenever they feel a need to.

This shouldn't be the case, but I think a lot of companies hire people that are technically illiterate to run marketing and they just chase eyeballs.