In my own personal experience, I wouldn't say a specific occupation makes teaching difficult, but basically the student's lack of interest or motivation.

If you find yourself teaching a specialist from any field, you know you have to learn -if you don't have it- the vocabulary and expressions, that is, the lingo.

Then, you adapt all you know, to fulfill a program or syllabus. I have taught firefighters at an international airport, I could say that was an extreme situation because the classroom was around 5 yards from the runway, and with every plany landing or taking off, I had to make a pause in the class. Firefighters are like all male groups in an action movies, you have to bond, and they gave me a hard time before I did. After I proved I was worth teaching them, they did as I said, and they also learnt!

I hope I shed some light on your question...