JimL
Beer can cold is only accurate if your outdoor conditions never change AND your indoor conditions never change. I have never seen a place like that but I must assume that you live in one or you would not recommend such a procedure. If you think I am wrong, ask the people that make the equipment. They recommend suction superheat or liquid subcooling. Just ask Lennox, Trane, Carrier, Goodman, York, Rheem/Ruud, Heil and others. All are providing charging charts based on something besides "Beer Can Cold".
If the Air Force did things your way, they would still be flying biplanes with cloth covered wings. Come join the 21st century.
Yes, there are some dishonest HVAC folks out there. I put them in the same boat as the incompetent ones. None of them are doing their customers or our industry any favors.
Stretch