Normally someone would have a tasting to show off the diversity of flavors associated with a kind of alcohol. Vodka aspires to be tasteless, so it's not like you're going to get much diversity from it. So it's better to look at a flight of vodkas as being a test - who can be the most tasteless of the bunch.
This is probably one of the factors about why I don't post about vodka. Another factor has to do with its popularity. Practically everyone who drinks hard alcohol will have had vodka at some point in their drinking lives. It's as common a mixer as coke and the primary ingredient in most martinis service today. Vodka shots go down quickly and when chilled tend to pour like water. Not that anything is wrong with this popularity - it just seems easier to abuse something you can't taste.
Take the fine drinking stock of the Russian people. Last week, The Lancet released a study that claimed 43% of deaths in their sample were attributable to hazardous drinking. These habits were both garden-variety overconsumption as well as drinking non-potable forms of alcohol in cologne and cleaning solvents.
But best be wary of wagging a finger at the Russians. The cheapest bottle of the hard stuff is almost always vodka. With a low price point it becomes a cheap default for people who want to get drunk.
Ironically enough, vodka is tarred with the same problems gin had over 100 years ago. In so many ways, vodka is the new gin.
Sorry for the tangent - this actually has a point. Since we aren't supposed to taste vodka, here's a test. Four vodkas of various origins to see if there's a way to draw out taste.
The first part is to get the stuff out of the freezer. If vodka is "frozen", you aren't likely to pick up any volatiles or impurities. That's one of the big reasons you keep the stuff in the freezer. Once it's at room temp, open the container and take a huge snort of air from the bottle. That'll be the alcohol fumes and possibly anything else that's going to be volatile at room temperature.
Now pour some into a wide-mouthed glass like a rocks glass or a brandy snifter. Swirl it around and take another noseful of the aromas. It should smell similar to the noseful from the bottle, though this time it might be easier to pick up the source of the ethanol. The most popular are wheat/rye and potato, though nowadays you can get vodka made from things like maize, grapes, barley, soy, and soon from pineapple juice. And it's not that each of those sources creates a different ethanol. They just have different volatiles that act as a signature for the kinds of ethanol in the vodka.
After a good swig of water to clean your mouth, take a sip. Don't swallow it; the point is to let the ethanol fume into your nose and let what's left stay on your tongue. This is the start of when flavors come out of the vodka. They might be a subtle banana flavor or an odd butter tone. But these are the things that made it through the distillation process and ended up in the bottle.
Finally, one last abuse to the vodka to really bring out the things you shouldn't taste: salt. Refined salt does not impart taste, it enhances tastes present in foods and drinks. As a result, a dash of salt into a relatively tastesless substance like vodka and you'll have those subtle flavors jump out at you. For example, the "3" Vodka made from soy starts tasting more like a rum or tequila. Which makes sense since soybeans are more on the sugar end of the spectrum. The other three came from wheat so they have a bit of a pot-distilled gin flavor to them. Their excess flavors are a bit more subtle, but the salt does help distinguish some of the differences between them.
And the least flavored of them all? Reyka. There might be some wisdom in filtering your vodka through lava rocks.