Licensed Professional Geologist here, and licking is a totally valid method for distinguishing between mineral hand samples that have very similar properties otherwise. For instance, halite (NaCl, aka table salt) and sylvite (KCl) are isomorphous, which means they have the exact same crystal structure and are very difficult to distinguish using traditional methods. Halite tastes like salt, but sylvite makes your tongue tingle when licked. Our mineralogy professor told is it's the only reliable way to differentiate the two without actual chemistry analysis.

Nope, geologists are commonly associated with licking rocks, and basically for the reason you’ve shared.

Hell, I had a geology lab where we were explicitly told we'd have to identify minerals by taste.

Unfortunately one of the other criteria was testing how a mineral reacted to acid... Which was listed higher on the worksheet...

Didn't taste that bad, as far as acids go.

One dissolves in water, the other doesn't.
But licking also works.