We were just talking about that on the weekend as there is a pair of trouble dogs on my preferred route. We ended up modifying the route to avoid them this time around. Unfortunately one of the times I rode past the place (the dogs have charged every time) the owner was out with the dogs and seemed to be fully supportive of their actually nipping my cycling shoe on so I'm guessing that if I pepper sprayed the dogs I'd end up with a crazy person in a car with a gun chasing me....