Depends on the situation.
If it's at a demonstration, I'll only work with partners whom I've had significant one on one practice. I realize that anyone can make a mistake, and I'm not there to sabotage the demonstration, so I'll go along with the idea that "the show must go on." I won't like it, but it is your duty to be a salesman for your system at a demonstration.
To put it bluntly, a car salesman isn't going to tell you about all the defect tendencies of the line of products that he sells, or else he's going to be out of a job soon.
If it's in class, I'm expected to offer some resistance. If the techniques are performed correctly, where the Tori has good leverage and placement, then that resistance isn't going to interfere at all. My partners are actually quite grateful, since they know that they are using correct technique, and if they aren't applying things correctly, they would certainly want to know. I expect the same thing from them as well. If I do not have the correct technique applied, then I certainly want to know.
This does, however, mean that the people that are my partners can't be too thin-skinned. Normally this isn't a problem, else they wouldn't have been practicing such techniques at this level, but once in a long, long while, someone who might have too much pride in himself, might think that I'm "no-selling" his techniques in order to make him look badly in class.
This is far from the truth, and I would expect him to do the same for me in a classroom setting. How else are we expected to learn if not through our own mistakes? Rather than dwell on such things, and mope around, we should accept this, make corrections, and become stronger as a result.
