If hundreds of people pay way over the odds for a course which doesn't produce results, don't you think, in that case the brand name would crumble?
Quite the opposite - look at how Profi-Lingua is still in business despite doing an awful job in general and producing many unsatisfied students. Their marketing is second-to-none, and people always want to learn English.
I guess the only way to find out for sure is to see if all schools published pass results for courses, but this of course would never happen for reasons that either the schools charging too much would get embarrassed or that rubbish schools are identified would outweigh the possibility of finding the best schools in Poland.
There are unofficial results available if you know the right people, but whether or not they're genuine, I have no idea. And yes, I agree - it would never happen. In some respects, it's not fair either - I taught occasionally an FCE group who were told that they shouldn't attempt the exam. They did anyway, and failed miserably - and it was all their own fault because they were lazy, unmotivated and with a real problem with accepting their true level.
Yes, the BC is a brand, even well-respected, and yes I also think the BC CELTA course will become far more popular than any other CELTA course in Poland even though it uses the same tutors as were in IH BUT.....
It wouldn't surprise me. The British Council brand, for all the corrupt, jobs-for-the-boys-and-wives-of-the-boys nonsense that goes on with it throughout the world, is still exceptionally strong even in light of their cost-cutting and "refocusing". IH, for what it's worth, is hardly a reputable brand.
the point is the BC must, in part, be a good school or it wouldn't survive
I don't think they're bad, but Poland is littered with examples of bad schools that not only survive, but flourish - mainly due to excellent marketing. Look at Speak Up for instance - many unhappy clients, yet they prosper.