As I've said before on this site, I teach strictly on a moonlighting basis, as I consider it more of a hobby for me. However, I have been dancing for nearly 50 years and have lots of studio experience. Plus, I read, research, watch, review videos, etc. So I believe I am very much qualified. But there would be no way for a person taking lessons from me to know that beforehand, and I understand that part of it. So what I usually do is tell them the first lesson, which is heavy on review of what I teach and how I do it, is for free. At that time, I give the student all of the paperwork they need -- what steps I teach, which dances, how much is covered over a six-lesson set, etc. If they don't like what they are hearing, they aren't committed to anything. I have been to franchise studios and private studios, private lessons and group lessons, so I know I could easily be certified in any number of places, but I'm not interested in going that route. I guess what I am getting at is, if you choose an independent, moonlighting instructor you may strike gold, or you'll be led astray. Depends on how serious you are, and how far you think an instructor can take you. I have no delusions. If someone wants to be a world-class competitor, they shoudn't be fooling around with my lessons. If they want to be able to dance seven or eight dances well at parties and weddings, etc., then I can get them to about a silver level or so. And most don't care to get that far anyway it seems because it takes a long time.
My main intent, actually, has been to teach the reluctant types so they are confident enough to go on to the private studio I go to if they enjoy it enough.
Good luck, and I am sure you will know a good instructor fairly quickly when you encounter one.