I personally think flushing is more important than heat, and truckmounts excel at flushing
Totally agree with you Derek. Not only do t/ms' excel at flushing but they also give you the added benefit of heat.
Using the correct pre-spray as well as the right agitation, we can all loosen the crap in carpets. The secret is extracting it - (and then right to the base of the fibres). On a pretty standard carpet, I flush at 450psi using a total of 08 flow and only a t/m is adequate to extract appropriately.
As Shaun mentions - ' beauty is in the eye of the beholder'. - and yes, I can make a carpet look spotless using l/m, rag spinning, encap (or whatever you want to call it). The clients are content - but you and I, as professional cleaners, know that there is really a world of difference as to how clean the carpets actually are.