what makes a good chess teacher

The same things that make a person good at teaching in general i.e. not only understanding the material, but understanding what is useful for the student to learn at this point in their development.

Having said all of these great points is what makes it hard to find someone without going broke on initial lessons only to find out that person is not for you

I was watching some random chessbrah video, where I expect drunken silliness, not anything remotely intellectual... but I was really impressed when this GM (not Hansen) was giving really good advice (IMO) to players rated under 1000.

It was something like "the opening principles say minimize the number of pawns moves so you can get your pieces out quickly" when in a certain opening position a move like h3 was played.

Instead of going into detail about the various aspects of the position that made h3 good, the GM simply said something like "Exceptions exist in chess. This particular position is an exception. If you play this opening then remember it. Let's move on." 

Simple, true, and didn't distract from the lesson at hand.

I've seen many coaches offer reduced rates or even free lessons to help you know if they're a good fit.

And if they don't offer, it's worth asking.

But also, like Pfren said... it's more than giving advice or (even worse) playing games (coach vs student). A good coach gives you homework.

In chess, and anything else, 99% of the work comes from the student. No one can make a person learn anything. A good coach clears obstacles from the road, but the student still has to run the marathon

That’s GM Aman Hambleton. He’s great for teaching and entertainment as well. He also co hosts a few of the chess.com tournaments with  GM Robert Hess who also deserves a shout out. I enjoy following his streams over Eric’s funny enough.

Aman is currently doing a speed run and habit sessions on the fianchetto bishop lines as white and black which is awesome because I play the English, Dragon and Modern Defence.

Coaches in the past I have spoken too deterred me from my opening choices so it’s refreshing to see a GM teaching and demonstrating successfully.

Yes, I guess I was talking more about somebody that would coach you, not a YOUTUBE guy.

I love some guys on youtube Gotham etc, but he's not going to coach me

It’s tough when I like Levy because he makes me laugh so hard but his playing style does not suit my taste.

Following a stream and discord does get you more information and improvement over YouTube alone but then it becomes an investment of more money and social time.