Unfortunately, there is no way to be 100% sure the vodka is real just by looking at the bottle. The only way to be sure is by tasting it. I haven't heard of this problem at Jenny Lou's, but I assume it isn't impossible that they have sold fake booze without knowing it too. Btw, the "stoli" that you drink at basically any cheap drinks drinks place or "all you can drink" nights is Chinese vodka called AnTe, but you probably won't taste the difference in a mixed drink anyway, and it shouldn't be any more harmful to your health than real Stolichnaya. AnTe is not the same as what is inside the fake stoli bottles, which doesn't even taste like vodka no matter what you mix it with.

The problem of fake booze is most common with Stoli vodka, or if you just ask for vodka tonic, vodka orange, etc. If you specify for a different vodka, say absolut or finlandia, you should be a bit safer. Also, whiskey, gin, etc. don't seem to have as many problems, though there are never any gurantees, and I've heard of fake just about anything turning up from time to time.
One rule to remember, if it seems too cheap to be real, it probably is. Case in point, I saw an ad for 200rmb Chivas with 5 btls of green tea and popcorn at a popular student place in wudaokou. Even if you're a huge place like Mix that sells tons of Chivas, you still have to pay about 160 kuai a bottle wholesale, so do the math and see if they could possibly be making money if they were selling the real stuff.

We have just been informed of this web posting and would like to thank Guest123 for informing us, the Centro Management of their concern with the Vodka served. Being part of the Shangri-La group, The Kerry Centre Hotel Beijing only buys our alcohol from licensed and approved vendors here in China, as such we will be informing the supplier of the vodka mentioned of your feedback and will indeed remind our bar staff to be extra vigilant with regard to checking new bottle seals and noting down guests' feedback. For this particluar comment we have not received other reports, nevertheless we do take it seriously. Thank you again Guest 123 and we sincerely hope when you next visit Centro you will keep giving us feedback. A very concerned and committed Centro Management.

i think i must have had a similar experience. the other night, i drunk some vodka, it tasted bitter and after a while, my vision started to blur, my speech started to slur. after this i can't really remember a great deal, though in the morning, i awoke with a bad headache and a toothless forty-year old divorcee lying next to me.

such symptoms can only be induced by counterfeit alcohol - i'll be making further investigations next weekend, by personally collecting a number of samples at various establishments around town.