Incognito is Best.

I have noticed that there are a number of dog walking businesses around who have very visible branding on their vehicles. After giving some though to this I have decided against putting any advertising on my vehicle...the simple reason is this:  

If i were using a regular Dog Walker then I wouldn't want to advertise the fact that I'm not at home by virtue of the fact that a very visible Dog Walking Van keeps pitching up at my front door at regular times of the week.

I am sure that this extra visibility is great for business but I have taken the view that i'd rather get a few less enquiries than alert 'perps' to the fact you aren't home.