Well, I’m not familiar with Adler, but I too have always preached that one should trust actions over words or intentions. In a world of deceit, one can only believe the actions that are made apparent to us. As a retired master of manipulation, artful bullshitter, and professional liar, I am well aware of the ease and deftness of deception.
I do not support paranoia. I often trust easily, at least on the surface. I find it easier to trust to a certain degree, but to keep a skeptical mind in the back, cautioning you and alerting you to any signs of danger or deception. Awareness and a healthy dose of caution can keep away many mishaps.
But the scary part is that a person truly dedicated to deceiving you will very likely do so. I would know: I’ve done so myself. Those with a strong intuitive sense of people, knowing what they people want to hear or how to phrase things in a way that will be accepted, these are the people gifted in the art of persuasion. There are those who have the gift of selling you an illusion, and there really isn’t anything you can do. The best kind of salesman is the best kind of liar. All they have to do is believe, and if you can believe in anything, you can fool everyone. The only way to truly avoid all deception is to trust noone, and verify everything. And that, my friends, is paranoia.