Wonderful input -- my compliments to the responders. Here's my take.
What we're talking here is odds. When you get a puppy from a well-respected breeder, you tend have better odds -- better, not perfect -- of knowing what you're getting both temperment-wise and health-wise. A well-respected breeder has the history of many of his or her Shelties going back many generations -- often back to the early 1900s. However, such breeders rarely know in detail the history of every single puppy they have ever bred because they've not kept and monitored every single one. The best I know in this area of watching her Shelties' pups doesn't know all of them -- there's just no way!
So, it does happen even in the finest lines that the genetic dice sometimes "crap out" on you. For example, Bitsy Boodle, possessed of a sweet and cheerful temperament (unless food is involved, whereupon she becomes The Intimidator), has a better pedigree than Queen Elizabeth and tested clear on every puppy test available in 2006 -- yet she developed early onset arthritis in her hips and has a liver enzyme deficiency. So despite the finest bloodlines, unanticipated health problems emerged.
Colonel Underpants is the sole offspring from the mating of the #1 ranked U.S. male Shetland Sheepdog (total points) of 2005 (and, maybe 2006 and 2007 -- not to mention his achievements in Japan and Canada), and the #1 ranked female of 2007. His temperament is sweet and gentle with his family, suspicious and anxious with strange humans, and fear-aggressive with other dogs. This year he was diagnosed with a genetic neuromuscular condition that had never in history been reported in any breed outside of Whippets and Greyhounds. This boy has baffled the best canine geneticists in the world -- yes, the world. Who'd a'thunk?
Layla came from the same breeder. She and Colonel Underpants have the same dam, and his sire is Layla's great-grandsire. Layla's sire, owned by one of the top Sheltie handlers in the country, is also a champion whose offspring read like a Who's Who of Sheltiedom. To date, Layla has never been sick, never been to the vet for anything beyond her spay in 2006 and her shots. Her temperament is beyond compare -- she's known at Walter Reed as The Stepford Dog because she is too perfect to be real.
So from one highly respected and successful breeder, we have three different stories.
Now comes Annie Laurie, our rescue girl. Annie came from a backyard breeder. Her dam was Mary, and her sire was Nacho Midnight Cowboy. Please note the absence of "Champion" with either. She was not physically abused to our knowledge, but she was kept either outdoors or in a garage, and was apparently sometimes yelled at and called "stupid." She came to us at age five leery of men and snappish with children. She fell in love with DH within 10 days and is convinced that the universe revolves around him. The feeling is reciprocated by DH. Annie Laurie is also the smartest of the bunch by a wide margin. Outside of some age-related arthritis, Annie, now 11, has been remarkably healthy. She is built like a cross between a credenza and a Sherman tank, would eat nails of she could digest them, and loves the world. The world loves her right back.
So you see, sometimes the odds are "ever in your favor" and sometimes they're not. Respected breeders will always take back a dog (note: not always for a refund) -- in fact, the best breeders specify this in the sales contract. Many rescues have the same policy.
So what does it come down to? Ever been to Las Vegas? I recommend you pick your best game, play what you can afford, and laissez le bon temps rouler!
