Ankle biter dogs and their untrained yappy owners.

As background, I'm a painting contractor and often work in peoples' homes. I also get to know many dogs this way.
About five weeks ago I was bitten by a Dachshund named Rudy - hard enough that he left a red mark on my shin, biting through my jeans. I showed up to give an estimate. Homeowner opened the door holding a toddler and the dog just lunged at my leg. "Oh, you OK?" asks homeowner. "He does that. Usually I put him in the kitchen when I answer the door because he's so protective. Sorry." Protective my ass.
I ended up doing the job, and Rudy barked hysterically every time I walked through the door. Bear in mind, these people had two toddlers and she was pregnant. I'm guessing Rudy was good with the kids - I sure hope so! These little dogs were bred to go after badgers, they are tough little dogs and capable of damage.
Last week, I went to another job. The homeowner peeked through the door - "Hi! Hang on, let me put the dog in another room." When I went in, I told her having a dog around didn't bother me. "Well, she's a pitbull..." That's fine, I said. I like dogs, as long as she's OK with me. Lola was a very nice, well behaved dog who did that cute submissive smiling thing. Owner told me her neighbors hadn't spoken to her for six years, since she brought the dog home from the shelter, but the dog was excellent with her grandkids and she'd taken Lola to many obedience classes so she would behave. Poor owner took pains to make her dog well behaved, and just expected people to be afraid and hostile because of the breed.

Clearly not all Dachshunds are ill trained and snappy, and not all pitbulls are sweet. This just illustrates a common difference in attitude and care between responsible owners with a larger "bad rep" type dog, and the millions of people with poorly behaved, untrained "cute little" dogs. I could relate tons of anecdotes like this. The main difference is training.

One more - see if you can spot how many dumb mistakes the owners made with their dog. Last November I spent a week painting for a very nice, childless couple with a much doted-upon, three year old Miniature Schauzer.
Every morning when I showed up, someone would have to hold the dog while he thrashed and barked like a mad thing, with Doting Parent cooing and shoving treats in his face. "There, there. It's OK. You remember her. Shhh. Good dog, have another treat." Well duh. Of course the dog is going to act like an idiot, they're training him to do exactly that.
Day one, I'm putting dropcloths down on the kitchen floor. Schatzie is sniffing around, then trots out of the kitchen and he's left a big puddle of pee on my dropcloth. Now if I'd caught him in the act...I called out to the guy, Schatzie peed on my drop cloth! He came in and told me I mustn't use water to clean the floor, only this special floor cleaner, handed me the cleaning supplies and walked out. Excuse me??
Lunch time, they fixed me a sandwich and we all sat down to eat. Schatzie was leaping up and down like a ping pong ball, actually trying to grab food out of our hands. Doting Parents merely handed him bits of food in response. They were like sweet, dumb Golden Retrievers - clueless but easy to train, and that smart little dog sure had them trained. I asked him to sit for a bit of my sandwich (when in Rome and all that...) but was told "oh, he doesn't do tricks." Tricks? "Sit" is just basic obedience and manners - this dog was three years old and had been taught nothing! Tricks is balancing food on your nose like a trained seal.
Day two, both humans left for several hours and asked if I wouldn't mind taking the little terror out to pee. But, they said, make sure he's always on his leash, because he runs away and won't come when called.
When they left, I had some fun. Man, was that a smart little dog and he loved to learn! I taught him to sit and down for a treat in about two minutes flat. We played recall games on his flexi leash outside. Just for fun, I taught him to jump up, off and over the ottoman. For the next several days I worked in that house, Schatzie ignored his humans and followed me around, delighted to show off his new "tricks" whenever I asked.
Doting Parents kept joking that not only was I painting their house, I was training their dog. I told them how smart he was, how much he enjoyed learning and tried to get them to do the same with him. Clearly, they never would. Poor little doggie. He had so much potential and spark, but was relegated to a boring life of being coddled and indulged. He'd forever be an ill-mannered little dog, never given the chance to really have fun. Because his owners "loved" him and thought it was mean to ask anything of him, I guess. Poor little doggie.
A well trained dog is a happy dog.
An untrained, snappy dog is a less happy, fearful dog.
It's not the dog, it's the owner. Duh.