But it's not in the handler's best interests to claim that their dog alerted them to the presence of drugs when they don't actually find any because that just makes them look stupid.
And you know this how?
All they need to say is that there *were* drugs in the car or that wad of cash has drug residue on it. There's no formal review process for use of the dogs and a lot of times they are used as a threat to people who refuse a voluntary search of their car without any real cause.
If you think a K9 is going to be called out and they are just going to walk away when he doesn't hit you are seriously deluding yourself.
No one here is questing the ability of the dogs, they are questioning the integrity of their handlers.