[Chunga]

A bloodhound can track a human being's scent for miles through car exhaust.

[bill1952]

So?

They have often led searchers astray on many, many documented occasions, failed to pick up trails on just as many occasions, and make mistakes every single day, just as any number of professionally trained humans do.

Dogs are not some robotic super beings from the planet Tarth.

They are living animals that are used as investigative tools, and as such, are subject to all of the faults that any living thing can make.