This isn't really an answer to your question, but a couple of observations. Some people are naturally gifted teachers. We must hope that many of them gravitate to teaching in one form or another, working either with children in schools and colleges, or with young adults in further and higher education or with adults in what, in the UK, is euphemistically known as the Lifelong Learning Sector. In the widest sense, dance teachers can fall into any of those groups, but many are self-employed and work in a commercial setting, but some do it just for fun or as a paying hobby. In most areas of teaching, training and certification is mandatory. You cannot teach children in the UK at all unless you have a suitable degree and post-graduate teacher training certification. You cannot even teach hobby photography to an evening class in a public sector college without at least an entry-level teaching qualification (PTTLLS), and if you have responsibility for curriculum development and management, higher-level qualification is required, even for flower arranging. I'm not wholly convinced that all this certification is strictly necessary, but I can't think of any compelling reason to hold teaching tango as being intrinsically different from teaching anything else. If I wanted to teach photography, I would hope to have enough confidence in the course of study I had undertaken to believe that it would help me to become a competent photography teacher. Dance teaching qualification is by no means limited to the BR fraternity. My society offers teaching qualifications in Ballroom, Latin, Classical Sequence, Salsa, Freestyle, Rock 'n Roll, Line Dancing, Cheerleading, Dance Exercise and Argentine Tango. Other societies do Ballet, Tap, Latin Club Dances, Belly Dancing, and goodness knows what else. In my society, candidate numbers for Freestyle outnumber those for Ballroom severalfold. As far as I can tell, the only members of the wider dance community with hangups about BR are tango dancers. I've never been able to work out why. No one could stop me from setting up a dance studio offering all or any of these styles, without certification. And to the best of my recollection, no student has ever asked me about my dance qualifications. They are of value to me, and only indirectly to my students. By and large, trained teachers teach better than untrained teachers. Would it trouble you to have open heart surgery from a self-taught medic?