I'm a Tampa FL carpet cleaner and I get asked all the time about these spotbots and other spot remover portables. I tell them that they work fine but I don't trust the solutions that you're supposed to use in them. A lot of the spot remover manufacturers have really soapy detergents in there cleaning solutions. To much soap can create a sticky residue that will attract more dirt to the area.
In most cases spot cleaning your carpet can be done just as easily with a good carpet spot remover spray and some towels. My favorite way to spot clean is to pour carbonated water on the spot and then suck it up with a small wet-dry vacuum. You will remove as much of the spot as you would with a spotbot or any other spot removing vacuum. I can't remember how many times I cleaned my own carpet with water and a wet-dry vac. I tell my customers who own a carpet spot remover that they can use it just fine but to ditch the cleaning solution and use just ordinary tap water. If you're able to get to the spill right away you will get most of it out without having to use their soap.
Take it from a professional carpet cleaner, I say save the money and just get a good spot remover and a $20 wet-dry vac from your local hardware store. Spot cleaning carpet should be easy and affordable.