I certainly had a mixed bag of teachers when I was in the school system. Some I loved, some I hated.
Some were pure evil, others loved children and making learning fun. This was back in the days when we got paddlings and some physical punishment was acceptable. But anyway, the best teachers were the ones that got a certain look in their eye when they taught, a look that said, "I feel passionate about this and you will too!"
I never got a teaching degree, but I have taught a few times. My favorite was teaching first and second graders Sunday School, and in the summer, Vacation Bible School. The other time I taught at a college - an evening class in Antiques. The kids were easy and fun - LOTS of crafts and hands on fun while you learn stuff. The adults in my Antiques class were a little more challenging - how to not have a boring class talking about antiques......blah, blah, blah.
So I ended up bringing in people I knew that have these terrific collections of things - and collectors are people that have a VAST knowledge of something - so we all learned from that. And the other thing I did was FIELD TRIPS. Local museums, historical neighborhoods and houses - seeing history and understanding the tools and everyday items they used for living life before all of the conveniences we have now.
So, I think the best teachers have to love what they do - and not do it because it pays well and has good benefits - but do it because they love sharing knowledge and would do it even for free if they could.