The problem with HMC coatings is that almost anything that touches them, especially liquids, leaves spots or streaks. These are not permanently damaging. They simply reform in other areas the next time you clean them. It's terribly irritating.
When the ones I have get dirty I have had luck by fully immersing them into mildly soapy water for a gentle full cleaning. Then thoroughly rinsing them in running standard tap water, followed by re-immersing them into distilled water, followed by an air dry with no touching, just like film. Doesn't always work perfectly, but it's far and away the best approach I've come up with.