A very common neighborhood complaint concerns owners' cats who are allowed to roam free outdoors and spray on neighbors' property, around their doors, and window sills. Cats do this to mark their new territory and to mark that they've been there.
Male cats tend to spray more than females, and tomcats more than neutered males.
Free-roaming cats may use neighbors' flower beds and vegetable gardens as their toilets, which can be a health hazard. It is best to start right by not allowing a kitten to get a taste for the outdoors. Cats adapt well to indoor living, especially if you have two cats to keep each other company. Better still, build an outdoor enclosure for your cats. Then if they wish to spray, they will do it outside in their enclosures and offend no one.