Dogs can authorize searches: http://reason.com/blog/2013/02/19/scotus-approves-search-war...

And to get this power, all the dog has to do is to pass a training program. That's like giving anybody who has a "diploma" from a "prestigious Internet university" powers to arrest and imprison. Only in this case you can't even argue with them because how can you argue with a dog? A dog barked, thus search is authorized.

Now let's think - can there be any ways to make the dog bark? If somebody does that in order to make foolproof instant probable-cause-on-demand, what would be his risks that the dog will grow a conscience and tell everybody he's been lying for years?