According to the Associated Press, "There are more than 70 million dogs in the United States, and they account for a good chunk of the nearly $3 billion pet owners spend each year on grooming and boarding, according to the American Pet Products Manufacturers Association."
A recent AP story looks at the rise of self-service dog wash centers -- For $8 to $17 at these places, you can take Fluffy and give him a bath. In someone else's tub. With someone else's soap/towels.
It's a good compromise for people who don't want to spend the $35 or more on a professional groomer, but also don't have the facilities to bathe an Alaskan Malaumte in their homes, or don't want dog hair clogging up their drains.