We have all seen a lot of movies in which police officers taste a small amount of powder to determine if it is an illegal drug or not. I was wondering it this actually takes place. Can police actually tell if a powder is a certain drug (thereare obviously some limites) just by tasting it? That must be some strange testing! Is this for real, or just Hollywood crap?
I remember reading a thread on this subject a while back. IIRC, the consensus was that it’s mostly total crap. I think someone said cops may put a bit on their tongue to see if it goes numb, but only in rare cases. They almost always have a quick testing kit in their trunk.
Maybe somebody with lots of experience at tasting heroin and cocaine could distinguish them from other bitter-tasting powders, but it would probably take quite a bit of experience.
Whethe it actually happens in real life, I’m not sure, but if it does, it probably happens a lot less ever since that possibly-true-possibly-urban-legend warning went around to police departments all over the US about drug manufacturers who were setting traps for police by leaving ricin around their labs. Tasting a tiny bit of cocaine ordinarily wouldn’t hurt you, but if it’s actually baby powder laced with ricin, you’re in big trouble.
My dad used to be in the UK Customs & Excise Drug Squad. He almost had a fit whenever he saw this sort of thing on TV. Just think about what they are doing - they are putting in their mouths a sample of an unknown substance of unknown purity. It is not unknown for drugs to be cut with some very nasty substances. It is also very unprofessional to be seen taking any quantity of drugs. Even if the amount is far too small to affect your performance, a defence lawyer would have a field day in court.
I saw Kojak do it once, and he was the man.
Do you mean on or off-duty? 
In all seriousness, do the taste test with amphetamine would give you a buzz. Called a “dab”, if I remember right. Not sure of effects with coke and heroin, but it would likely show up in any blood tests, and not sure “I was just tasting it” would qualify as an acceptable excuse - certainly not nowadays.
I always figured that any movie drug dealer with half a brain should carry a few bags of cyanide in the trunk of his car… there isnt a law against that, is there? 
Having worked police dispatch–no, no one ever tastes unknown substances. There are test kits usually consisting of little (like 1.5-2 inches square) plastic baggies containing a reactive agent in a breakable container. You pop in your powder, seal the baggie and break the reactant tube (like playing with a chem-light). Shake your baggie and look for a color change. Voila! And no, Sardaukar, from what I can see in my state’s RCW’s, nothing illegal about carrying cyanide as long as you filled out the poison register and didn’t lie about anything–but I bet they’d get some really, really interesting questions about why they were carrying it (by the survivors, of course).
Just to give a little of the “hollywood crap” perspective here…
Countless activities as portrayed on TV bear little or no relation to actual practices (foremost perhaps being courtroom procedures, at least for current shows). I’m sure that’s not news to anyone.
The way certain professional practices are portrayed on TV is mostly determined by dramatic impact, but also by speediness. Authenticity comes in a distant third. Most images of TV cops doing the “finger test” come from the 70’s and 80’s, I’m guessing before sophisticated test kits as Bestet describes were developed. The finger test makes the cop look like a badass and also takes a hell of a lot less screen time than pulling out some test tubes or waiting for a lab report.