What are some red flags for a CEO in a startup?

Lack of general work experience; lack of business experience and/or training; lack of management (people and project) experience; inability to speak or present confidently to a group; little or no understanding of the customer or market; and many more…

Lack of domain knowledge, micromanaging, or lack of willingness to take a stance. Startups need someone decisive, who knows the field, and lets their employees get shit done.

My main filter is the same as my BS filter, assuming they otherwise have basic competence and at least one strong leadership quality.