Its not a question of maybe, it works lol I can understand about not feeling comfortable with a QD since its very limited on what it can clean. And I can understand being cautious for heavy contamination with ONR but water spots n dust? Really? If its to that point of being uncomfortable with ONR why even use the product? as it would be clearly false advertising of what its suppose to do. I personally wouldnt support a company if the product didnt work...Or why not do a test area to get over your fears of the product?
First, it depends what "dirty" means to you. To ME, and this will not be the same for you or everyone else, "dirty" means anything that is caked on. IF dirt is beyond the point that I believe I cannot remove it with one gently wipe of waterless wash I wont use it. It takes tens of hours to properly polish a car, I wont risk that to save 30 mins.
What I will do is, spray down the vehicle with some waterless wash and then pressure wash the car, then follow with a application of waterless wash again and dry with detail spray.
This is how I use the following, again you and everyone will be different.
Detail spray - To DETAIL, or freshen up a "clean" vehicle.
Waterless wash - Dust, very mild soiling from everyday usage, smudges, bird bombs etc.
Rinseless wash - slightly more soiled then the above, but only with a pre spray of waterless, I never rinseless wash with out spraying down the section with waterless first.
2 Bucket - any kind of baked or caked on dirt, if you can still see the dirt after you sprayed it with waterless, (ex. when you spray down light dirt it looks like its just wet,) i'm giving it a 2 bucket wash.