Few people realize their SHEM63W52N already has a water softener. This is the white version of a 300 Series family that sold in huge numbers: 44 dBA, 16 place settings, a third rack, a deep tub and condensation drying. Look at the floor of the tub and you will find a cap over a salt reservoir.
In a hard-water kitchen, such as many in Houston, a reservoir left empty for years is the usual reason glasses turn cloudy for good. Etching of that kind does not wash off, and neither does a fresh start with salt.
Machines of this model have now reached the age when the rails under the third rack and the springs that balance the door call for a look, and a service visit is a good moment to fill the reservoir properly.
That is the filler cap of the built-in softener. With hard tap water you feed it dishwasher salt, and a charged softener keeps scale film and slow glass etching away.
A film of scale will clean off. Etching cannot, because that is the glass surface itself being eaten away. One descaling cycle normally shows which of the two you are dealing with.
It depends on water hardness and how often you run the machine, so look in the reservoir whenever glass starts to cloud. A machine left dry for years is what causes lasting damage.
Book in about a minute, or call the desk. Same-day windows inside the Loop on most days, next-day across the rest of Houston.