That is a good idea. The commitment might get to you after a while. I mean, I have never had kids but the exhaustion from waking day-night from it might be a lot on poor old you!! Then the other thing to consider is on bad weather when you prefer not to bundle Alyson up and go outside the owners might assume you are. I've seen someone get huffy over this, even though they
were too lazy to take their own
dog out but I've seen it happen. I know it sucks that people are stupid and don't take their dogs out and most of these dogs are energy-ridden smal terriers but you have to write down all the pros (obvious - extra cash, exercise, relieves the dogs of energy, bonding etc) and the cons (weather, customer reliance, scamming etc).
If you decide to go with it, I would recommend starting at a beta price. Like 10$ per hour/walk or match it with whatever minimum wage is there. Add more if you intend to release them at a park for play or of you just intend to walk around the block. Consider the socialization of the dog(s) in case people have dogs they want walked from the building but which don't get along with each other. I think it's a great idea though