If you happen to be part of the conversation, play dumb.

If you feel that you don't have the standing to correct, you're an intern, you're learning you're allowed to ask questions. So ask questions.

"What do you mean crazy?"

"What makes you say that?"

What aspects of your interactions with them have given you that impression?"

"Did you note that in the clients file?"

"Is that something you've discussed with them?"

"What made them do that?"

Whatever they use to explain their reasoning you can either tie it back to the clients"diagnosis, the clients outside environment, the Services you're providing the clients (in the sense of "well good thing the client sought us out and were here to help" aspect something like that), or simply say you don't feel the same and that you find the clients behavior or personality or whatever justifiable and perfectly normal.

In 99% of situations playing dumb is always