Yeah, but we haven't seen too many good ATF used oil analysis.
And, I do understand that smell/color was even out-lawed in certain states because quicklubes use smell/color to sell an ATF flush.
I will still use smell/color, along with odometer, as a simple method. Sorry, but I don't care what the automakers, lawmakers,.... say.
Its almost impossible to overmaintain a vehicle. If you have more then 30k opn ATF, IMO, regardless of the fluid used, you are overdue for a flush. If you want to prove me wrong, simple spend the money for a used oil analysis.