The problem they cause: Not understanding what a coach even does, how to properly coach - nor what the intended outcome of coaching is supposed to be, they ruin teams rather than establish them.
A year ago, I myseld would have gotten a decent score on this list, and even today, I'm still learning. It is through my contact with a few select, truly inspiring coaches that I have learned the difference.
If you think you're a coach, you can use this list to reflect. If you are looking for a coach, this list is a non-extensive (potentially growing) list if things you want to look out for. Careful: A job interview may not be when you discover the signs. I observe my peers at agile conferences and meetups - and thus, this list was compiled: