You need to undestand that there are many different views on the proper way to wash a truck, deck or house. That is part of the reason that we have access to these boards. Some people swear by acid for trucks, otehrs use only on aluminum, and still others refuse to use it anywhere. Hopefully, the people involved in the discussion will make their point and try to understand the point of view of others. I know that some guys like Coastal Eddie, and Bigboy use Acid on anything, and everything, but I would bet their dilution is really weak so as not to minimize the reaction with whatever it is they are spraying it on. Ideally, with any chemical, you want touse the minimum amount to get whatever grime you are trying to get off, off. Anymore is just waste. They may have it dialed in more, or do all of their own work so that they can predict the results, versus letting employees do the work and risk that they will follow instructions.
Scott