Yes, I know. Why would a sign writer implore you NOT to have your van sign written?
When you are a completely inconsiderate tradesman, that is when!
If you go to the trouble and expense of having your van sign written and carefully installing a builders board outside your customers' premises, then you are in the 25% of tradesmen actively trying to market your business. You understand that nosey neighbours will take note of who is working at Mrs Brown's and may see it as an unsaid testimonial should they be in the market for your trade in the future.
But DON'T ruin all that hard work by parking inconsiderately outside your customer's house. I am sure you won't be that person that drops litter every where out of your van. You certainly wouldn't be inconsiderate enough to block the kerb for pushchairs and mobility scooters. And I am sure you wouldn't shout and be generally discourteous to all the traffic that is beeping trying to get passed you on a busy A road . . . .
I know this because we only have nice customers . . . and our nice customers grow their business, not ruin it.