quite often folk expect too much from a snow foam. A gentle ph neutral foam will loosen dirt prior to the wash stage but not remove heavy traffic film etc. on cars that have stood under a tree for years then something more agreesive would be better (citrus pre wash or similar). Used safely, a traffic film remover or all purpose cleaner through the lance will shift a lot more but also eat away at waxes and can certainly stain plastics/rubbers etc if left to dry. As stated above, all these are pre washes and are done prior to your bucket job.