I'm sorry, but I have to say--WTF?! That is kind of disgusting, because there are PLENTY of dogs in the shelters that need walks. Why not just go down to the local humane society and volunteer to be a dog walker. That'd be a LOT cheaper and a LOT more beneficial to the dogs.
And if it's so sad that there are dogs in the shelter, if you think about it, dogs being rented out isn't much better. People are making a LIVING off of RENTING these poor dogs out, causing them, no doubt, all kinds of mental trauma, and if they're not already owned, they never will have the chance to be owned...