The answer to your questions and comments involve specific jurisdictions and professional bodies (boards, colleges, orders). I can’t speak for much outside of Quebec, where I live and work, since it’s the area where I am most familiar with the rules and regulations governing psychologists and the practice of “psychotherapy”, which is a term and practice protected by provincial law in terms of what it is, and who can offer it. Things may be different where you live.
In Quebec, in order to do psychotherapy, you must be a licensed psychologist, trainee supervised by one, or an allied health care professional (e.g., psychiatrist, psychiatric nurse, social worker) who is approved to do psychotherapy by the professional order of psychologists (the OPQ, Ordre des Psychologues du Quebec). Each state and province has its own professional body who would field complaints of “bad” therapy, investigate the therapist and act to discipline them. Unfortunately, although the terms psychotherapy and psychotherapist are protected in some areas, there are people who get around this by calling themselves “life coaches” or something similar, so that they are ungoverned by any laws or governing body. In that case, you get what you pay for. It’s like going to a someone for legal help who isn’t a member of a state bar association. So, it’s in the consumer’s interest to consult with your national or state professional organization governing clinical psychologists prior to choosing a therapist. Most people do this for insurance coverage purposes anyways. The national professional organizations (in the US, it’s the American Psychological Association) are primarily advocates for the profession, and can help you find a licensed psychologist in your area, but they are not directly responsible for discipline and investigation. If you want to file a complaint against a psychologist, the Association of State and Provincial Psychology Boards is a good place to start, as they maintain a section labelled “Public” (which is on a crummy Web site so I can’t link) which specifically gives advice on how to do so in your jurisdiction and a list of state and provincial board contact information.
That’s for psychologists. If your therapist is a psychiatrist, you’ll have to seek out the local medical board. Same for nurses or social workers, they each have their own governing/licensing/supervising bodies.
As for hanging out your shingle with little investment, I’ve been in graduate school and supervised practice/internship for over six years (yes, beyond my Bachelor’s degree). It’s not the kind of thing you just decide to do on a whim.
In terms of your comment about therapists struggling with their own mental illness, well, those disorders are present in a sizeable percentage of the population at any time, and therapists are often vicariously exposed to very dark things, so there may be even higher percentages still in the profession. With that said, we are all encouraged to get peer supervision to help with the difficult cases, and seek out our own therapy when needed. One certainly doesn’t need to have been addicted to successful treat addiction, nor have had an anxiety disorder to treat anxiety. I do know therapists who do treat disorders they’ve dealt with personally, but I also know many that do not do that, for fear of being overwhelmed. It really depends on the individual, and what they think they can ethically treat. Yes, a shared experience can help with therapy, but if the therapist isn’t careful, it can also lead to false assumptions about their client’s actual experience. So, it really depends on treatment modality and comfort level.
Hope this helps.