For the needs of police, any dog COULD be fine.for sniffing, nothing beats Bloodhound or Beagles..obviously less offensive to the public/crowd. need to adjust the situation when using a Rottweiler or an Alsation or a Melanois as sniffing dog (unless its your partner in patrol). large breed (attack) dogs are a lot to control and they respond decisively (which is good in certain situation).
The #1 dope sniffing dog for the US Border Patrol is a Pitbull rescued from a shelter. The problem is both improper training and not enough practice for the dog.
It is very difficult to keep a dog "on task" in an uncontrolled environment like a junkies car at midnight in a rain storm.
Many police departments do not do enough to limit false hits by their dog. If their dog hits, they get to bypass the 4th amendment and search the car.
There are military German Shepards that are 100% on explosives, which can be more difficult to detect than drugs.
The military DEFINITELY discourage false hits.
Its not the dog, its the handler and the handlers intentions that are the problem.
Many dog cops can't even get their dog off a bite.....ive seen the videos.