If this is the case, then most likely you're dealing with a 'corked' bottle of wine. Here's a quick explanation of what exactly this is and how it happens.
What is it?
Basically, any wine that has been infected by the organic compound TCA. It gives the wine a nasty aroma, often compared to damp cardboard, wet dog, or mouldy newspaper. At worst it makes the wine completely undrinkable, at best it will just mute the natural flavours. There are various other organic compounds that have a similar effect (TBA, TeCA etc), but TCA is the main culprit.
How does it happen?
Mostly it is a result of using an infected cork to seal the wine bottle, but the wine can also be infected by taint compounds present in wood or rubber in the winery itself (barrels, beams, rubber tubes etc). The latter can be disastrous for the winemaker - wineries have been levelled in the past in order to stamp out the problem. This explains why it is possible for a screw capped wine to be corked.
The Cork Oak can be harvested every 9 - 12 years. It is always done by hand and no harm comes to the tree.
How do the corks become infected?
TCA forms when Chlorophenols interact with naturally occurring, airborne fungi. Chlorophenols are present in some pesticides, so if these are used in cork plantations then trouble may be afoot.
How to deal with it?
Not easy, but Andrew Waterhouse (professor of wine chemistry at The University of California), reckons that soaking the wine in cling film can do the job. Apparently it sticks to the Polyethylene in the cling film. I haven’t tried this but it sounds like it would be worth a go, particularly if you’re dealing with a melchizedek of Lafite... might be a bit of a fiddle though.
- Bits of cork floating in the wine do not mean the wine is corked.
- Mould around the top of the cork does not mean the cork is infected or that the wine will be corked.
It’s also worth pointing out that wines can be spoiled in other ways. Oxidisation being the main culprit – if the wine is exposed to too much air (for example due to a dry and therefore leaky cork), it will taste a bit like vinegar.