Plus ça change
The concerns of the wine snob worldwide may soon be set to rest. A study conducted by the Leatherhead Food Research Association has suggested that plastic corks can taint wine producing an "off taste" which may cause health problems. Furthermore, the Association is advising that wine with plastic stoppers be subject to EC regulations on expiry date labeling, which could result in some interesting new developments in the discussion of wine vintages.
We would advise you deal with plastic-corked wine the same way you deal with corked wine. Swill the wine around the glass, inhale its bouquet, and if it's off don't drink it.