Decision Tree : how to determine target in a model with no labels?
Use Clustering under unsupervised learning. That will categorize the customer based on similar parameters. You can define the number of cluster you need to form, in you case it is two(trustworthy and not). If there are more features it will be more helpful for the algorithm.
This might help.
https://towardsdatascience.com/an-introduction-to-clustering-algorithms-in-python-123438574097