[hutzlibu]

Yes, that is wrong "than this is all that matters in court". There are some exceptions though, like with tax evasion, then illegal evidence was excepted, but in general you are right.

Still, in case of the dog: it would be interesting, if there was a case about it, as I am very sure of the practice in reality.

Police will do, what works and with what they can get away. Most people will just comply when the police tells them to open their pockets (note that they don't have to articulate it as an order, the same if police comes to your door without a warrant and they ask if they can come in) assuming the police has the right. (and drug addicts usually do not have a lawer).

I don't know if it would hold up in court as a justification for searching, that a person looked nervous because of a police dog as the person just could have fear of dogs in general, so they likely would avoid it.

(Also, if you happen to live within 30 km of a nation border like me, then police (Zoll) can search pockets and cars all the time without concrete indications. So they could use this tactic without problems, but I have never seen the Zoll doing it, but the normal police in the cities)