I've gone through the process many times. Most partnerships were failures. The only startup that succeeded was with this guy who added me on Facebook after I bought his book.

But by far, I find that the strongest indicator of a good partner is whether you're adding them on Facebook.

For one thing, partners that avoid you on social media are a little dodgy. Some would even see you as an adversary - this guy they negotiate against, that they're going to leave when business is over, that we're splitting equity with.

And often there's some subconscious disgust to people you're not willing to add to your friends list. The reason for this disgust often becomes clear in about 3 months. But we have years of experience with people - if something is off about them, we'll know.

The best partners to work with are the ones who you want to get closer to. The ones who match with you on an ideological level. The ones you feel that you can learn a lot from. And more importantly, the ones who you consider a real friend, or truly want to be friends with, and are willing to go to long extents to help.

If you feel the need to test this person just because they have a nice business model, I'd suggest that they've already failed the test.