I get water spots too. I figured it was just hard water stains. Sure is annoying!
That is when it started happening to me when my Condo put in front loaders - I was secretly blaming neighbors for using softener or have greasy cloths but they to have the same issue. I have not been able to get them out with rewashing - but will try the murphy oil soap trick next
I dont use those anymore just that ball for stopping static
One thing I know it is not the dryer since it happening to my good shirts that are dried on a rack
That is not true of my spots - they are cauuses somehow by the front loading washer