The very wise and very successful Saad Khan says that he only invests in "badasses." I'm on board with that; given the likely length of the investor/entrepreneur relationship, life's too short to waste on people you don't like.
Yet like many simple rules, it's incomplete. Investing in great people is a critical part of being a VC or angel investor, but I liken it to casting a great actor--even the greatest actor can't overcome a bad script.
Meryl Streep has been nominated for an Oscar 17(!) times. She also provided the voice of a queen ant in "The Ant Bully." Scripts matter.
The thing is, even though scripts matter, the performer matters more. Meryl Streep can make even middling scripts (e.g. Mamma Mia!) look pretty good. The greatest script in the world can't win Megan Fox a Best Actress Oscar (sorry, Megan!).
The ideal thing for a movie studio or an investor is to find a great actor who has a knack for finding great scripts. Clint Eastwood won fame starring in the TV Western "Rawhide," and could have spent his entire career playing cowboys. Instead, he formed his own production company, and created a long series of great works, including Best Picture winners "Unforgiven" and "Million Dollar Baby" (both of which also won him Best Director Oscars).
You should definitely ask if an entrepreneur is a badass, but it also pays to ask if she knows a good script when she reads one.