I think that it can be very helpful to verbally establish boundaries up front. And I don't think boundaries should just be about a T's limit they should also be about the clients needs. When I started with my current T I told her that I didn't want any hugs because touch can easily trigger obsession for me. I also don't want her accepting gifts from me for the same reason.

For you Clinpsy you might consider telling your T that you need consistency and that discussion of things like what your appearance has to do with your sexuality is off limits, or at least shouldn't be taken as a sign of anything in particular.

You might also consider thinking of boundaries in terms of hard and soft limits. For example, Emailing might be a soft limit for some T's where they are willing to accept the occasional email, but going to a T's house would be a hard limit.

I think what is most important over all about boundaries, however, is that there is an open conversation about them, and that the conversation is not a one time thing. Everyone in the relationship needs to be open to discussing their needs, and should do their best to be honest with the other person about what those needs are.