i do think a T needs to have hope for their clients. i mean, what would be the purpose of seeing them if they didn't? if a T really didn't think they could help they should refer the client to someone other T. having hope for the client doesn't mean the client will necessarily grow though. the client has to do the work and they need to have a good fit and working relationship with the T, etc. etc. if a T can't believe in the client, especially when the client may not yet believe in herself, then i'd think that T is not a good fit.

in your specific situation RTS i guess it would really depend on her tone and body language of how she said it to get an idea of what she meant. if it was said jokingly or with a smile like she's really impressed with you that would be one thing, but if it was more serious or doubting then i know i wouldn't feel comfortable with her. i think it is fine to give her another chance and ask her why she said that and observe her response. it would probably tell you what you need to know about her.