I agree with the OP that trustworthyness is a key requirement for building a successful co-founder relationship. What I can't work out is how you would measure

I agree with the OP that trustworthyness is a key requirement for building a successful co-founder relationship. What I can't work out is how you would measure trustworthyness or (perhaps more importantly) how you would establish if you are good at measuring trustworthyness.