The majority taking beginner lessons from a world class coach has no reference on which to draw... it takes yrs of experience ( at a prof. teaching level ) to even understand some of the concepts ( which all do not hold water ).. discernment comes with age and experience, and, I stand by my original statement, that there are numerous teachers that can hold their own, particularly for a beginner level student .The proof is in the quality of work turned out .
Also, take into account the different styles being taught by several of the current top coaches.. from the "Italian" to the "English" style concepts ..... different trains of thought, both with merit .
Its just another way of describing the " wheel ", everyone thinks theirs is better ! .