I hear that about all herding dogs. Just as I hear that terriers are prone to biting and are not usually good with children, but that's obviously a blanket statement.
The particular "bad" traits of any breed usually manifest whenever they are not brought up with the right discipline. A Corgi or other such dog who nips at any human's heels has a problem with dominance and doesn't know their place in the family "pack". I do try to take great care to help socialize my dogs so they understand their place in the hierarchy of our household (people, including children, always take precedence), as that makes for a much happier pet.
I suspect that there's also a lot of "small dog syndrome" in many of these smaller breeds too.
