The Under $20 A Bottle Wine Thread:

Originally Posted by Fumes

Dirty tricks afoot in the cheap wine trade: The Great Wine Cover-Up.

As the article mentioned, it's not just the cheap wines. Not all the tricks are dirty.
These kinds of articles get published from time to time but I treat it like sausage making. Sometimes you don't need to know exactly how it was made.
There have been similar articles and posts about the tricks cigar makers use, ie. maduro dyes.