Steam Cleaners and Soap Scum on Shower Doors

I adore my steam cleaner. However, I think you need to clean the doors first and then use the steamer after to keep the doors clean. The best product I've ever found is Don Aslett's Showers 'N Stuff. I buy a gallon at a time and use it in a spray bottle. Nothing even comes close to this stuff. I used it on a fiberglass tub that was stained brown that nothing would clean; this cleaned it in no time. Great, great product, and I wouldn't use anything else. No affiliation, just a huge fan.