Yes, Friends, life is the best teacher.
If you want to know if you can trust someone, sometimes the only thing to do is give them something of minor significance and see what they do.
When you do this, you will get a clue concerning trusting them with a more significant responsibility.
This technique is good to use when you hire someone; consider someone for friendship who comes on to you a little too eager to help you. Even when you raise your children.
How you handle the outcome is your choice. Start by trusting a little, then maybe trust more or dismiss them (of course, you can not treat your children as if they were friends or employees).
Having musical acts proved some musicians and singers wanted to usurp my leadership. As a supervisor, some employees wanted to undermine my authority or define their role contrary to the premises they were hired for.
A Dom/Sub relationship has many of the same aspects. Having a contract can go a long way to alleviate potential problems. And, make clear the consequences when an agreement is violated.