Instead of mental illness, it might be more fitting to say mental health.

Sometimes it's obvious. Other times a therapist tells the client. Other than that, I agree with you-how would a client know?

When searching for therapists, it was obvious when one presented very needy for my approval. This was by the second session. Another one encouraged me to email him after the first session. Someone can very well interpret that in different ways, but with all the context, I thought he was lonely. I likely would have never noticed these things had I not done the type of therapy I've done.

It may seem kind of mean to say, but after my experiences, it's self-protection. I have been very vulnerable in my therapy and for that an other reasons am prone to being harmed.

Maybe it doesn't matter to others as much, but also a therapist would have to have worked through their issues in their own intensive therapy for me to consider them. It wouldn't be as much of a big deal if they were an issue oriented therapist, maybe for coaching or short term CBT. But I am speaking as a trauma client.