It's definitely not the dogs; it's the owners. They see you coming and start calling their dog or yanking on the leash, usually getting the dog right in front of you as a result. Or worse is a dog on a leash in a tunnel, with the leash stretched across so there is NO place to go. With an iPod, naturally, so the owner can't hear you! At least when I've had to stop to avoid dogs, the owners have apologized instead of trying to blame me.