question about camping with a pittbull

My dog has been dog aggressive a few times in the 10 years that we've had her. Only 1 of these incidents ended up in a dog fight. An unleashed dog wandered into our campsite. That dog ended up with a little mark on it's nose. The owner from a few sites down apologized and agreed my dog was not at fault and I didn't say anything about his not being on a leash. Since then we're always alert to a dog possibly wandering in our site or walking up to us when we're walking our leashed dog. We run into at least 1 in every park that the owner will just not put the dog on a leash. As we approach a wandering dog, I'll change direction with our dog and my wife will try to distract the loose dog. 9 out of 10 times the nearby owner will yell "oh, he's fine, he loves everyone!" and that's when my wife answers back "well mine doesn't!" I really wish owners would realize that leashing their dog not only protects people but it also protects their own dog.