Best Buy conducts "in-house" training, for the most part, conducted by people that we originally trained.
As mentioned, they can not do harm to a set, as would have been the potential in the "old days". Are they as skilled as someone who has been devoted to the practice for the last 12 years? That is for you to evaluate.
Please let it be said once more that while someone attends the ISF seminar (20 hours of instruction over a two day period) and successfully passes the 100 question exam, all the ISF is "certifying", in a defacto sense, is that the candidate has been in attendence and passed the exam. We do not lend any credulity to their skillset nor acumen. Realistically, how could we?
A great barometer to gauge the abilities of anyone in question is their résumé and their ability to produce referral information. Many seen contributing on this forum have built solid reputations for integrity, attention to detail, honesty, and dedication to the science.
The program at Best Buy was designed to create a wider awareness of the benefits of calibration, and make it more accessible to the public. However unlike a "raw" product such as a DVD player, for example, where there is a certain expectation of "repeatability", the same assurance cannot be made when the factors of human interpretation and educational adaptability are introduced. Consider it like officiating in sports. Those officials that rise to the pinnacle, let's say the NHL, would be expected to have and are held to higher standard, than the volunteer at the pond hockey game.
Please understand that Best Buy is doing a fine job of executing this program. It has proven successful, and the number of video displays that are left unequivocally with better image quality are more than ever anticipated when the ISF was founded 14 years ago. Can the fallability of humans render an occasional less than desired result? Of course, as in any profession. Naturally our affinity sours when we are on the unfortunate side of such an incident, however, Best Buy and all independent, reputable calibrators assure the client of their satisfaction.