The only real way to identify if someone is a hustler is by knowing if they’ve actually done any "hustling". People who have their own projects, whether it's a full blown business or even a side-business, are voluntarily using their free time to work. Passion and the hope for a better future is what fuels them. If a person has no problem putting in work for their side-passion, they may also have no problem doing that work for an employer so long as that employer can also ignite the fire within them.