The only credible sources of info on real therapy outcomes, that I'm aware of, are forums like the one. And when I read the forums I see a lot of troubling stuff, and not many cases of clients walking out of therapy and into the light. If there is some other way to judge the effects of therapy, I'd like to know what it is.

I think nobody knows how often therapy is damaging, and precisely how, because nobody cares, unless something happens that is too terrible to ignore. Everything else is simply ignored, or is explained away by endless excuses and rationalizations -- client has too many issues, client is resistant, it's a "process", gets worse before it gets better ... ad nauseam. Harm is never really harm. It's an opportunity for growth or some such manipulative drivel.