That is to say, drug dogs are extremely effective, it’s just that their job is different from what their name might make you think.
As long as it doesn’t result in evidence being thrown out, a drug dog that alerts when drugs aren’t present is a feature, not a bug, for the police.
To put an even finer point on it, drug dogs don't need to establish probable cause, and they don't, they just provide a back door around the 4th Amendment.
Legally they check the box, which is the important part.
Yes drug dogs need to establish probable cause, that is how they meet the requirements of the fourth amendment.