I see the problem, it's ok if it's just a bit of mud or dirt but a real stain starts making your anal sphincter start to twitch
A bit of red wine or Ticka Masala and you run for the hills.
This offer will go on my leaflet which goes out in a 4 mile radius of my home, I will not have to go out of my way to do them, I have a spot pro machine so need need to set up the truck-mount, plus I get most stains out. This will be a minimum, quick £30 and it gets me on the house.
I can see why some wouldn't have the confidence to do this but I don't see stains as a big deal.