I apologize that it took me so long to get back to your post. Long day at work, obedience club meeting, and a somewhat rough night... but better late then never I figure.
It strikes me that you left out a few of the corrections you use.... and I don't think that gives a full picture of what I was responding to. I saw no mention of a "pop" on the muzzle, or your earlier advice in this thread to grab the muzzle, or that bear hug thing (that really just sounds like a modified alpha roll, where you confine the dog until he "submits" to your "dominance"). I would also imagine, from personal experience, that collar corrections are a part of the training picture. No, I'm not accusing you of going out and beating your dog... and I highly doubt that any of your corrections are physically harmful to him or her. But the risk of backlash or backfire from these types of techniques is very real... and evidenced by another poster's bumps and bruises. Sure, the risk with pushing your dog into a sit is minimal (unless he has issues with his rear being handled), but when you get into the really murky waters -- separation anxiety, other anxiety issues, resource guarding, aggression -- that risk is even greater. Or what about the bear hug you suggested? If a dog truly lashes out against it, the risk of a bite to the face is remarkable... and what would an incident like that mean for most dogs?
But really, the biggest thing that struck me about your post is that I think you have a misunderstanding of what I was referring to by positive based training.
Let me clear up a few misconceptions here:
There is no such thing as "pure positive" training. My mistake for phrasing it as I did, but I've yet to find a good, all-encompassing name that everyone has agreed on. In real life, there is a duality to the quadrants... with positive reinforcement comes negative punishment. There is a consequence to making the wrong choice.
There's nothing inherently wrong with letting your dog know verbally that he made the wrong choice. In modern/positive/clicker/whatever-you-want-to-call-it training, the most common form of this is the No Reward Marker (NRM)... essentially it says to the dog "wrong, try again." There are plenty that do use the word "No" under certain circumstances, though the ways of reinforcing it generally differ from coercive training.
Calling a dog over and over and over again until he decides to stroll over and figure out why the record is skipping
isn't "positive" training... it's poor training and really, really bad advice. It's unfortunate that the "positive" class you've enrolled in has an ineffective trainer leading the class, but that does not speak to what other trainers are doing.
The focus in this kind of training is asking the dog only for what he is capable of giving you. I often cringe when I hear phrases like "he knows what that means," or "she's just blowing me off," because they're so frequently untrue. Sure, your dog may know what come or sit or down means in the kitchen, but that doesn't mean he knows it in the back yard. He may know it in the back yard, but that doesn't mean he knows it in a training facility. He may know it at class but that doesn't mean he knows it at the dog park.
This type of training requires a large initial investment in helping the dog to generalize tasks... you may have to take a few steps back when changing a major criterion such as location... and when people are unwilling to put in that initial investment, they never do see the results. The good news is, the more behaviors you generalize, the easier and quicker each subsequent one becomes... but how many people never make it that far? People would rather assume that once a dog has learned a command in one place that they will naturally understand it under any conditions... and when the dog doesn't respond, they give a "correction." From then on out, all teaching that occurs in the new environment is coercive... so, I'm sorry, but the "I always initially teach positively" claim doesn't really fly.
Ignoring a dog for behavior, such as jumping, that has been previously rewarded (sometimes intentionally, usually not) isn't an easy row to hoe either. The nitty gritty reasons for this would likely double the length of an already long post, so I'll try to put it as succinctly as possible. Initially the dog will redouble his efforts looking for that reward (even if it's just a verbal correction or pushing him away, or whatever he is interpretting as the attention he craves). If you give in then, you've only reinforced that longer, harder effort and dug your hole deeper. If one decides to take this route, they have to absolutely commit to 100% consistency, because each falter only strengthens the behavior. It does work, but only if the person is committed to making it work even as the behavior hits a fever pitch (known as an extinction burst). If you can make it through that, you've won the war... and if the behavior does re-emerge at any point down the line (sure, it happens at times), as long as the person remains consistent, it is an easy fix. And yes, that was the short version, LOL.
Look, I'm not just someone who drank the Kool-aid and has no idea what's on the other side of the coin. I've trained my current dog both ways. I grew up with your typical dominance, physical, coercive training (complete with happy, friendly initial teaching stages). When I got Jersey, I just figured that was how you trained a dog. And then I found myself with a dog who was very outgoing, and yet lacked the confidence needed for upper level obedience tasks. When faced with a puzzle he didn't know the answer to, he would shut down.. because he knew the wrong answer would be met with something unpleasant (despite the fact that were were still in that "initial positive" phase... he was just waiting for the other shoe to drop, because inevitably it always did). So I decided to do something different.... I threw out everything I knew, or thought I knew.... and I started from scratch. A dog's confidence is built by giving him the tools to solve the puzzle, by allowing him to be successful, by not asking more than he is capable of giving. Yes, there are still rules, yes there still need to be cut-and-dry rules... I'm not advocating a free for all. I just see a different way of getting there, and only wish I had found it sooner. I now have a dog confident enough to think things through, to risk making an error, and to try again if he is wrong. Almost 4 years in, it's like owning a new dog.
Honestly, if your methods work for you and you have no interest in changing, then that's your prerogative. But to off-handedly state that this training won't work for a particular type of dog (or as you later stated - any dog) is a disservice to those looking for ways to modify their dog's behavior. This training does work and it fosters a relationship built on trust between dog and handler. But as with any training, timing is key... some methods are more effective than others.... and most people need guidance to understand how to implement it effectively. With the information and tools available to people today, thanks to the internet, this "do no harm" type of training should be the first line of defense in any behavioral snafu.... especially with the inherent risks involved in using physical force.
At the risk of making this longer, I do want to clarify that I am in no way suggesting that you should not offer training advice to people simply because I disagree with you. I wouldn't dream of it, and in fact I hope you do continue to do so. Truthfully, telling more specifically how particular methods didn't work for you (whether it's you talking about positive methods or me talking about coercive ones) is probably the best learning tool on this forum. It helps to keep others from making the same mistakes we have and allows everyone to clarify with tips and tools to make each suggestion better. But I do take exception to those types of blanket statements and will continue to answer to them when given the opportunity.
I'll now end just as I began... with an apololgy. I'm sorry this post is like 16 pages long... but the effect of having to sit on this all day until I could get to my computer is that I had way too much time to think about things I wanted to say.

: Hope you have (crap... had) a good night!! Thanks for the lively debate!
Julie and Jersey