Other discerning readers will have their doubts too. I agree with what you have said. Maybe it's worth adding that it's likely that cautious jobseekers have googled the names of particular training centers that have recently placed adverts for upcoming job vacancies next term, only to come across negative reviews. Some of them will have informed said training centers of said reviews. As it will be in the intersts of said training centers to minimize the negative impact of those reviews, they have 'papered over' in public by posting favourable reports about teaching at their TC's. The posts have been submitted by DOS's and/or their lackeys!
Of course, the same problem will be experienced by schools/colleges/universities that have high turnover rates of FT's. But ask yourself why it is it that there are considerably fewer complaints on this board about the directly aforementioned educational institutions than there are about TC's!