One of my best friends is an HVAC tech (he installed the unit I mentioned above). After hanging around with him for a few days one summer I was amazed at the shoddy workmanship on most HVAC installs. "Quick and dirty" seems to be the order of the day all too often. Most of his work is coming in and fixing what wasn't properly done in the first place.
Unfortunately, his attention to detail can also be his worst enemy. His installs easily take 30-50% longer than competitors installs because he goes to the trouble to clean and seal the ducting, manifolds, and air boxes. He also takes the time to adjust motor speeds to match airflow needs/restrictions, actually charges the system properly instead of throwing refridgerant at it and hoping, and takes time to actually balance the system. As a result his quotes tend to run high and his billable time on repairs is more than some. This means longer and more expensive installs and repairs, but installs and repairs that work extremely well, have far fewer callbacks on workmanship issues, and usually work more efficiently than the exact same system installed by a less conscientious installer. It loses him some customers, sure, but the customers who do use him are fanatical about it. They won't even let a tech from the same company come work on their systems. It's Brian or no one.
I suppose the problem of shoddy work is born of competition to get in, get it done, and get it billed. I also presume that the general public, with it's complete lack of knowledge about just how intricate and complex even a small residential HVAC system can be, drives the industry into a corner. It forces providers to "fix" things in the least time so they can remain cost-competitive, even though the fix may not be as thorough as it possibly could or should be. In this context, the public's unrealistic expectations really have created the problem - techs who do shoddy-but-fast work in order to meet the public's grossly ignorant expectations of time and money.
Brad