As a service tech for 20+ years as well, I disagree. I have installed Carrier, Trane, Lennox and a few others and in my opinion Janitrol stands up there with all of them.
In my experience (and yes I have screwed up installations) it is all in the installation. Undersize, oversize, poor return vent, etc. cause problems for any manufacturer. Take a look at other manufacture threads - you'll see just as many people upset over Trane, Carrier and Lennox. Remember - 40% of people will go out of there way to "bad mouth" a product when they have a bad experience, but only 5% will go out of their way to praise a product they have good experience with.
Goodman manufacturing is putting the squeeze on HVAC dealers that sell the overpriced, highly advertised products with the misconception that "their" (read Lennox, Carrier, York, Trane) is a better product. Spending less on advertising and more on manufacting a quality product benefit those who do research and understand that no manufacturere would stay in business in this particular "heavily regulated" industry.