Update: I think I have strayed from the point being argued with this. I want to keep it up since I wrote it and I don't think it's bad, but I realized in the shower this doesn't address what TimToady mentioned. Sorry 'bout that.

If mistakes happen, then the subject has not been effectively communicated. No matter what opinion the communicator may have about their communication.

A little ambiguous, but I get what you're driving at. (I don't think ambiguity is a mistake, but it does hinder effective communication.) As I understand it, you're saying that if a mistake were to happen during a certain communication, then the meaning of that communication is ineffectively conveyed. If that is what you meant, then I disagree, mostly because other aspects of the context can disambiguate the meaning so that the communication is effectively conveyed. I have, on more than one occasion, said a wrong word to refer to a referent, yet the other person I'm talking to a) understands what I meant to say and b) didn't even stop the conversation to make sure. Usually after a few minutes, I realize I didn't say the right word and attempt to correct, yet the other person responds there is no need for me to do so, since they understood exactly what I meant to say, even tho' I didn't say it. I wasn't correct, I was wrong: but the meaning was still effectively conveyed because of the context. Of course, that's just my understanding based upon what I have experienced. I take your two sentences above contradicting what I have experienced, and therefore I'm partial to my experience.

Maybe a few (or many) years after the fact, someone listening in on the communication (without the segment where I attempt to clarify) might not understand what I meant, and then we get audial criticism on the part of the new listener to discern the meaning with whatever vestiges are left of the original context of the communication. But that problem is a different one for me, since I see social, economic, et c. environments as being a part of a certain communication, and without immediate access to that context, the communication is assuredly not as effective. (Yes, I see effectiveness as a gradient.) Anyway, I know I can be wrong, since it's already happened many a time, but I'm just trying to explain why I think I'm right. Hopefully I'm being effective. :-)