That's an industry that is all about you. If you are pleasant and do good work, that's about all it takes to keep busy.

I too have used a car spa treatment. Every few years I let them at my wife's car. I do my own as need be but these car spas do a bit more and all at one time. My method is to deep vac one day then shampoo the next, then next weekend more work so she won't get the instant tadah effect from me.