This issue tends to pop up from time to time everywhere. For myself I've noticed that it doesn't happen to me anymore seeing as I'm the instructor of the class now rather than a student. It would take someone really cocky to try to tell the guy teaching the lesson he's doing it wrong
Not that thats beyond the realms of possibility mind. But it hasn't happened to me yet.
What I have had happen is things go a bit wrong when demonstrating a technique in front of the class, if I have a beginner for an uke and they don't know what is expected of them things can go a bit awry. It happened this week in fact. My chosen uke was supposed to be attacking me ushiro tekubi tori but rather than grabbing my other wrist once he was behind me he just kept charging along having no real clue where he was or where he was going. It took a lot of control on my part to stop him planting his own face into the mat
When this sort of thing happens to me while I'm teaching the lesson I usually just laugh and explain what happened and ask uke to do it again until he/she gets their part right so that I can do my part (demonstrating the technique we're about to practice).
I have also had people come to Aikido from other martial arts backgrounds and look at what I'm teaching with a critical eye, I really have no problem with this in any way. My feelings on the matter are simply this: If I can't explain it properly, then I don't really understand it myself. Which means I've found something else I need to learn
My experience of people from other MA backgrounds coming to Aikido is easily described by lumping them into two broad categories.
1 - They have their curiosity piqued and keep coming back
2 - They think Aikido (or the instructor who happens to be teaching it at that time) is a load of rubbish and they leave.
I tend to find that those in category 2 come back when their joints etc can't hack all the stuff they want to do in TKD or whatever, then they reappear aged 35+ with dodgy knees, shoulders etc and wonder why they didn't start Aikido earlier.
PS - With regards to the original shihonage twist out thing. Easy, bend your knees if you're nage or when they're off balance midway through the twist let go and take a bold confident step straight towards them, they tend to fall over and realise that the technique doesn't have to be text book for them to find themselves on their backside.