I could make enormous amounts of money doing this. Because I always notice these mistakes.
There are signs on both sides of the glass doors at the entry to the building that I work in which say "No Hawkers or Canvases."
Even though I have worked in this building for many years now, every day that I work I have a little chuckle to myself at the thought of a building in which canvas artworks are forbidden. We are a government department, so we don't have a lot of fancy artwork on our floor anyway....but it is nice to think we are following the building rules.
As they say, small things amuse small minds....