They can be. We've become a magnet for the harder cases for some reason, so our latest, Marco, has been quite the handful. We've had a total of five so far though, and most have been good after some work. The thing to keep in mind is that racers only know kennel life, so when you adopt one at 1.5 - 3 years old, they will be like big dumb puppies in your house. They usually aren't house broken, don't know about things like stairs or glass patio doors etc. So it can take some work. But once integrated into the home, they are calm, loving and devoted dogs.