The old saying that there are no bad dogs, only bad dog owners is true. I have known people who had dogs that would have been considered as a breed to be gentle that were mean and would bite, nip and tear things apart to the point where you were scared to be around it. I have known people who owned rotweilers, dobermans, and other "agressive" dogs that were sweet and playful. Any dog can behave as agressively or calmly as any other. It is how the dog is raised that determines which way the dog will turn out.
I get tired of seeing people who are too stupid to realize that a dog or a cat is an animal and treat it in a inproper manner. If a dog like a German Shepard is playing with someting like it's chew toy, going up to it and putting your hand in its mouth to pull the toy out is stupid. A dog isn't smart enough to release its grip just because your hand is in there. If it bites you, you deserve it. If you pick a cat up by the tail or drag it around like my neighbors kids did with my Siamese cat, then you deserve to get bit and clawed.
I especially get tired of seeing people who own animals be poor animal owners. One of my neighbors falls into this category. They let their dog run all over the place, no collar, no tags, no leash, not in a fenced yard, etc. The dog runs across the street with no warning all the time. I have come close to hitting it with the car at least 30 times in the 5 years I've lived here. I've even slid off the road and into someones yard to avoid the thing. I get so pissed about that, but I'm not mad at the dog, because it's a dog. It isn't taught to look both ways before crossing the street. It is up to the owners to protect the dog, and if I ever were to hit the dog accidently, I'd feel terrible for the dog. I won't feel bad for the owner, they don't deserve the privlidge of having an animal.