Pills, even to humans, have a distinctive smell close up. To a dog who has thousands of times the "smell power" of us, it'll smell that distinct at a distance of 10ft and through a plastic bag (which aren't air tight).
Some people say "stick them in a jar of coffee" or "run the bag in chilli powder" to mask the smell. It doesn't work. If it did drug smuggling would be way easier. When you walk into a kitchen and there's pasta, vegetables and meat being cooked you can tell all three of those things are being cooked because you can tell the smells apart. Well a dog can do that too, even with more pungent things.
Most dogs are trained for cocaine, cannabis and heroin (heroin smells very much like vinegar due to the acetic anhydride used) but soem will be trained for meth or MDMA and can pick it up. Chances of you getting one of those dogs? Very low. Most police dogs (even thoses seen to be used as sniffer dogs) don't smell you, the police look at how you react. The little beagle dogs are the good smellers, be worried if you see them!