• Guide Dogs:
Based on the experiences of a blind friend and of a professional trainer friend in the USofA, and of GSD breeders in NZ, it is that modern trainers are dedicated to "get paid as soon as possible" rather than "produce the best product for each client", plus that many of those trainers are prejudiced.
The blind woman had 4 inadequate guide dogs in a row - actually, the first was fine as a guide, but it was constantly too ill (allergies) to work so had to be retired very early. A blind person can stay dog-less for a LONG time before a replacement is available, and without a guide dog cannot perform much in the way of office-work, etc. And when a dog IS ready, the blind person must go live at the training school for a while to ensure that dog & human are working together - not the ideal situation for a mother of toddlers, or a person in paid employment!
She ended up choosing a young-adult GSD in a rescue group, and training it herself - with the help of a sighted friend for setting up "traffic" situations. And is VERY happy with what she has.
Apart from a few pets used as little more than "mobile canes" by a few blind people, the original guide dogs were ALL German Shepherd Dogs. See "First Lady of the Seeing Eye" by Morris Frank. See "The New Knowledge of Dog Behavior" by Clarence Pfaffenberger.
However, GSDs are rarely mentally mature before 3 years, AND (like Border Collies!) they get bored by constant repetition (ever worked on an assembly line?). So they DON'T suit trainers whose "method" is to repeat a single lesson 30 times in succession - whereas Retriever breeds lap up repetition.
In addition, not many blind people are suitable for a GSD first time up. People who've never owned a dog, people who are cowed by a dog's ENERGY, are unlikely to maintain the training consistency that a GSD needs. And especially: People who have become so unconfident about moving that they just shuffle gingerly along are NOT suited for the speed a GSD prefers to walk at.
And then there's prejudice - sometimes deserved! Because the GSD is so popular, far too many are produced from parents who should have been neutered (often by owners who should have been neutered! Better: Their parents should!), with disastrous effects on behaviour & character.
The imported trainers who set up my country's first guide dog school wouldn't have a bar of GSDs. A couple of our top show breeders had to donate GSDs, to "force their arm".
• Police Dogs:
Actually, the police use several breeds, depending on what's best for the particular task. But for patrol dogs - which is what you mostly see checking out a crime scene or being used to quieten an unruly mob - when properly bred the 2 Shepherd Dog breeds (Belgians & Germans) are supreme. Both are the ideal size-compromise between small-for-agility but large-for-power; both were selected to have initiative + responsibility so that they could be left in charge of the flock (and the unfenced crops!) while the human went off to do something else; both were selected to have courage so that they could stand up to a hungry ram or a hungry predator (2-legged or 4-legged); both were selected to have endurance plus great devotion to their human "pack". Therefore what makes for a competent boundary-patrolling herding dog also makes for a competent security/protection dog.
Les P, owner of GSD_Friendly: http://pets.groups.yahoo.com/group/GSD_Friendly
"In GSDs" as of 1967