Considering all of the stories we hear over and over and over about the way the install bays at your average Best Buy are run then I would say in this particular instance speaking your mind was exactly the wrong thing to do.
No one here is saying that speaking your mind is a bad thing in general. But knowing (or at the very least you should have known) the type of response your interviewer was looking for and giving him something from the complete opposite end of the spectrum was likely not the brightest idea.
In the Big Box stores bottom-line sales figures are king and providing customer service is a secondary consideration at best. No, I am not talking down to those of you that ARE Best Buy installers but I would wager that your bosses run things in such a manner that you cannot with any degree of honesty contradict what I have stated.
Bottom line here is from what you've shared with us it sounds suspiciously like you talked yourself right out of a job.
/story.