When its job is to teach rather than to issue a diploma which other parties would recognize, attending a couple of lectures would be enough for me to see how well do they teach if it's worth my money. There should also be money-back warranty for those unsatisfied with the quality of teaching. At some point, if I were satisfied, I would also recommend it to people I know and such a recommendation would be enough for me to give it a try if I were them.

Measuring such a subject by thyself may seem like a fallacy as many people obviously don't think like I do but I believe there are many (a number sufficient to sustain a business) who do think the same way in such a big country.