The golf course I went to is built on a quarry - the course is very new and it was windy and sunny
So my car is in the parking lot and they had their sprinklers on - When I returned from my round, my car was covered in erratic water splotches of grey - I washed it the next day due to time but I guess the sun baked it in pretty good

Anyone have experience in what this does to the finish? - both a touchless wash and a Meguier's gold classic hand wash failed to adequately remove the outlines - I had to klass all-in-one it very aggressively or is this just a normal hard water splotch in the sun?

Since I am new to the car detailing game - appreciate any insights

 

It sounds normal - my guess is you got some mild etchings from very hard reclaimed water. AIO is a great product, but is just barely aggressive enough for the task. The best defense is one (or more) coats of sealant. By all means stick with Klasse if that works for you - their products are outstanding.