What I usually try to awoid and most of the time actually succeds in awoiding is criticising a person. I would expert other People here to awoid that as well.
There is a difference between criticising a tree: this is not a bonsai, what you have here is a mallsai, your tree is not a bonsai why waste your time on a small sapling etc... and criticising a person: you're stupid etc. These statements are not equal.
I am a professional musician, I've had long and difficult path getting where I am. I didn't get here because I didn't listen to people who gave me, often quite harsh, criticism. I got here because I let my first initial emotional response calm down, and then I thought about what the person was saying to me...it often hurt to realize that I wasn't going to easily get north by first going some other direction, but in the end, it helped me that people were 100% honest...
and here even more so... I've only killed about 10 trees in my 4 years, and only because of dumb mistakes repotting, and buying species that don't thrive in the conditions I have to offer(another dumb mistake).
ok.. with my first ikea ficus, Auk and I got into a bit of a discussion, but I eventually listened, and 4 years later, I'm still here, and I actually have a few trees that are not too bad and have gotten to be much better under my care... the ikea ficus is still alive, by the way.