I understand that as an agency you can’t always be picky. But the worst possible client is one who doesn’t trust you.
They hired you for your expertise. They hired you because you know more about ads than they do. So don’t let them micromanage you. Don’t let them tell you how to do your job.
The ideal client understands that you know more than they do about advertising. They might occasionally ask questions and get clarification, but they aren’t correcting your strategies or directing your every step.
If you have a potential client that shows signs of this behavior, run.
It’s not worth the hassle, no matter what they are paying you. If they think they know more than you do about how to run their ads, do them a favor. Let them run their ads themselves.
It’s just not worth it.