I consider myself to have a great deal of self confidence. And I only speak on subjects that I have done my research on. But I would never interject into another instructors session unless solicitted to do so or it was in my gym. I have observed instructors doing things that I would not approve of or that I thought were dangerous. If it was in my gym, I pulled them into my office. I explained that unless they could show me that the exercise was safe and had a purpose, they were not to continue teaching it in my gym. A few were able to do so. A few were offended, but the responsibility in my gym is mine and I am not going to allow a member to get injured if I can avoid it. If I saw this in someone else’s gym, I would point it out to the owner/manager if I felt someone might get hurt. And leave it up to them to proceed from there.
In forums such as this I will state the facts on a subject if I have done the research to support my position. I won’t do someone else’s research for them, but I will direct them to search topics that can clarify my position if they want to do some work and learn.
Egos should definitely be left at the door.
However, given that we are the professionals, I would say “bragging” and “informing” a client are very closely related. Having an understanding of the human body as well as experience in the gym is what people want you to have as you are selling yourself.
You dont want to hire a trainer that says “Yea, I know a little about the gym”.
People want to hire a trainer that is capable of pushing them to their limits, get results, but do so in a way that is not dangerous. The only way to get that impression across is to tell them.