Awesome article Marilyn. My experience has been the same.
There’s one thing I might add: personality.
Even a client with a perfect purpose, an adequate budget, and an opportunity for a great portfolio piece may end up being a nightmare to work with. They may be lousy communicators or have a rude and abrasive demeanor. In short, they make poor clients and collaborators.
I judge my potential clients on the same factors as you, but I’ve also learned that when you work with the right people, it almost doesn’t matter what the project is. I’d rather work with a great client on a project I’m slightly less passionate about (but still believe in), than one who’s criteria seem perfect on paper but they fall short on the personality required to make an ideal, respectful client.