Another potential red flag attribute I've witnessed is shifting of the idea deliverablee\objectives after the green light is given. A partner I once had developed a pretty great idea we decided to execute on after 20+ hours of planning. He started proposing entirely new (follow-up) ideas mere hours into our execution. Then started morphing the original plan. 1 week later he was dropping idea bombs left and right. I finally delivered something close to the original plan and he spent the next 2 months slowly backing out of the project entirely, having put in less than 10% of the effort.