The base is not a good diagnostic criterion for Chinese glass anymore. Most I've seen recently has been smoothly polished and quite nice. The only way I know to guard against buying Chinese is to know the piece of glass. Chinese glass is made to look like other types, e.g. Murano, Scandinavian, Czech, so it can be quite deceiving. Yesterday I checked on a few pages of glass being sold as Murano on eBay. The majority of pieces being offered were not Murano. The category having the most misattributions from what I saw were the little lampwork animals. Vases were also a bad category for misattributions.
The Chinese are very good at what they do and are becoming better. Sometimes it seems like a predator-prey game, where the glassmakers come up with ways to make their glass look more European, and collectors try to learn new ways to avoid their teeth. The sheer quantity of glass that is coming out of China is staggering. The only way I know to avoid Chinese glass is to buy books in one's area of interest. And even then, there is going to be the occasional Oriental bit that sneaks in. :or: It would be okay if the bit would be collectible soon, but pieces are produced in such quantities that it will take a while. At least the quality is improving, so Chinese pieces are excellent to use for house decoration. One doesn't have to worry about water stains as much.