When Ts have a reason to suspect a transference positive to the work is happening, they usually observe it and may encourage it. It's not beginner therapist work--it takes a lot of skill. I don't really see it as "trickery," but rather a standard psychodynamic way to build the alliance and meet therapy goals. But Ts will not usually bring up the transference directly until well into the process. They refer to it as the transference "ripening," and it seems to very much be a judgement call on the part of the T to know when the best time is for an individual. For me, it was pretty late in the process. And it was coupled with my T frankly discussing his own counter transference.

I think the exceptions would be if the transference starts to turn negative, it may be necessary to bring it to light to avoid damage; and in the case of an erotic transference that becomes obsessive or acted out, in which case it undermines therapy goals and needs to be confronted to have a chance at salvaging the relationship.

That you feel like it comes and goes makes me suspect it may be your own feelings projected, as Hazel suggested. Or it may be that during those times, you're sensitive to it, and other times, you don't notice it. Trying to hide it isn't very effective with a perceptive, experienced T who's also working psychodynamically because they're on alert for it.