I've found that I'm guilty of too upright torso in the squat, so this article is most welcome. For me the cue "chest up" before the start of each rep has somehow come to mean "keep my chest up for the duration of the lift", as I've had tendencies to shoot my hips up (and back) out of the hole without the chest following. As a consequence, hip drive is shit and the squat needs to be fixed ASAP.
How do you SSC's typically unfuck people's squats at seminars, do you have a set modus operandi? If I'm to unfuck my squat by myself and my video phone, would a good start be to lower the weights from usual work set weights and work on technique and using the "point your nipples at the floor" cue before working up in increments to or near previous work set weights once the technique is solid?