It is very hard to figure out. I am IMHO a savvy business person and even I have a hard time figuring it out. Ultimately it takes time and getting to know the person.
The only advice I can give to accelerate this process is to ask lots of questions. If he has an answer for everything, that's actually a bad sign as it typically means he's BS'ing.
You want someone who's humble enough to admit where he isn't sure what will happen or how things work.
Absurd certainty and BS'ing is ok although not preferred for salespeople. But it's a sign of impending doom for a manager, especially for a startup.
The only advice I can give to accelerate this process is to ask lots of questions. If he has an answer for everything, that's actually a bad sign as it typically means he's BS'ing.
You want someone who's humble enough to admit where he isn't sure what will happen or how things work.
Absurd certainty and BS'ing is ok although not preferred for salespeople. But it's a sign of impending doom for a manager, especially for a startup.