What you should add really comes down to your market and what people are open to. For example we added Holiday lighting this year and while we did fairly well for a first year we got a lot of weird looks because holiday lighting companies are far and few up here, where as in the south west there is a large holiday lighting market as it has been more polpular down there longer than here. One thing I would recomend is to check on the laws for mobile car washing. Many states regulate this very strictly and hold molbile car washing to the same standards as a large carwash/detail center. Here onsite carwashers have to have a way to reclaim the water off the ground and remove it with them in a mounted grey water tank. Many states and federal laws regulate that industry due to water runoff and diffeent water acts/laws (my family owns one of the Country's largest distributors for that industry)
Why do people not respect us as they do other tradesmen? Because every Tom, Dick, and Harry doesn't think he can be a plumber or electrician!