LOL! It's a normal scene actually. I have seen a few situations like this where there will be 3 - 4 newbies and 1 leader; easily identified. That so-called leader will be instructing and giving senseless advise like the guy on your this thread.

I kinda pity all the wrong concepts and exercises that he was giving them. Well, if it's me, I just don't bother. I go to the gym for my own health. BUT, if the guy really seriously give a wrong advice which will harm them, I will find the right time and talk to the other person whom the advice is given to.