If the man gets his hair really dirty, like farm dirty with diesel and moly grease and itchy chaff bits, then it means it probably doesn't have what it takes to do the job.
My wife bought endless shampoos, I tried them for sport and none ever impressed me. Our hard water laughs at fancy shampoos and soaps.
I always told her to forget it and use my big jug of Pert. A classic that says something on the back like "Pert wasn't designed to waste your time and money. Pert was designed to get your hair clean" but she was sure there was something wrong with it because it was only 5 bucks.
Finally one day she gave it a try and has used Pert ever since. It made her hair smooth and soft, it even washes moly grease out and it smells "fine", men's shampoo is the winner IMO
And now my shower is so tidy with only one jug of shampoo
Double would be a COP of over 10. That's a stretch for an overbuilt GSHP and not even slightly feasible for air-air.
High COPs are usually easy on a compressor as they represent low compression ratios and low differential temps. For example I can hit around COP 7 in cooling on my scrap heap GSHP, with an evap temp around 10C and condenser temp around 20C. That's a high side pressure around 100 psi and only 30 psi of differential, "barely working" as far as the compressor is concerned.
The only way I know to get high COPs is to have an oversized condenser and a way to get your refrigerant below ambient, like evaporative, ground source or overnight radiant so you can get the compression ratio down, unless you know a secret in which case I'm not afraid to burn out a compressor or two trying it out!