We’ve spent a fair amount of time in this space talking about what makes up a great teacher or coach. Today, let’s talk about the opposite. The bad ones. The ones who quietly steal your time and energy and prevent you from progressing as well as you could. The ones you want to avoid.

Confession: I know about toxic teachers/coaches, because, at various times in my life, I’ve been one. Both in the classroom (in graduate school, no less) and on the sports field (with my Little League team), I’ve been in charge of the learning process, and I have proceeded to do what I’ve since realized was a pretty terrible job. (I’ll spare you the details, but let’s just say that whenever I run into someone from one of my first classes/teams, I usually begin by apologizing.)

So with that in mind, I’d like to offer this brief, completely unscientific list of traits for which to watch.

1) The Courteous Waiter: This is the kind of person who puts all their efforts and attention into keeping you comfortable and happy. They don’t push you to the edges of your ability, but rather keep you in the comfort zone, glossing over any moments of difficulty in favor of a “we’ll worry about that later” approach. This kind of person is usually quite likable (think of that really cool teacher you had in high school) and because of that likability, you never learn much (again, think of that really cool teacher you had in high school).

2) The Charismatic Speaker: This is the kind of person who spends all their time talking. Lecturing. Weaving shimmering webs of ideas into the air. They’re often quite eloquent and charismatic; listening to them can be great fun. Which is precisely the problem — because in the end, passively listening to someone talk is a really inefficient way to learn. We learn by doing, exploring, discovering for ourselves. By asking questions, interacting, engaging with ideas. (Another reason why Socratic method works so well.)

3) The Remote Ruler: This person spends their time high above the playing field, designing strategies and methods, and rarely descend to interact with the people they’re leading. Some good examples of this type of teacher is found in the leadership of bigger organizations, like the NFL and Wall Street, both places where a culture of remoteness can easily take hold. This person often seems quite powerful, but they often end up failing because they overlook the most fundamental source of power: the personal emotional connections to the people they’re leading.

Finding the right teacher, coach, or mentor is sort of like test-driving a car. And just as with a car, it pays to lift up the hood. Go for a test drive. Find one who connects with you, who challenges you, and who pushes you past what you thought you could do. You’ll go farther.

PS — speaking of good teachers, I’m reading a couple really good books right now: What I Talk About When I Talk About Running, by Haruki Murakami (great on the link between endurance and creativity), and Thinking, Fast and Slow, by Daniel Kahneman, which is great on the relationship between impulsive and rational thinking.