As to thieves, if someone were "casing" your home, they will KNOW if you are gone or not regardless of an RV in the driveway.
Personally, the added portions of DSDP Don's "RV shack" would not detract me from buying the home. If I didn't like it, I would simply ask in my offer that he remove it upon sale - that way I don't have to deal with the dumping. In addition, if he were going to sell, it would be extremely easy for him to remove those additions before listing. My bigger concern in buying that house is that all the houses appear to be painted the same boring color - suggesting that there are rules that will affect my ability to make the house my home.
