Richard Neidich stated: "So, does that mean that Madiera is over
oxidized?"

Oxidation in reference to wine usually means chemical reactions that
cause some of many compounds present in the wine to combine with oxygen.
Some oxidation reactions produce products that are desirable, others
produce undesirable products. At least some oxidation usually is needed
for red wines, which is one reason why they are aged in casks that take
in a bit of oxygen containing air. Different wines, having a different
distributons of compounds in them, can oxidize in very different ways.
Some wines can be greatly oxidized to produce a wine that is much more
interesting. Madeira is a prime example. Sherry is another. Both of
these wines are fortified to some extent. At one time Madeira was put in
casks and sailed around the hot tropic waters to become Madeira-like as
we know it. Long ago it was found that this process could be duplicated
by heating the wine in large chambers for an extended time. Of course
the key here is that both Madeira and Sherry take up oxygen in the cask
at a fairly slow rate. In the case of some sherry that is long-aged in
cask, a flor film forms on the surface of the wine in the cask that
keeps things under control. Without these special treatments that
involve considerable oxidation, the base wines for sherry and madeira
would just be not-very-interesting normal wines, in many cases.

For normal table wines, different wines respond in quite different ways.
Some of the classic Rioja whites were kept in cask for even decades and
gained great richness without a nasty "brown" taste. On the other hand I
often find an over-oxidized Chardonay to be rather nasty tasting, flat,
and rather bad smelling too. One of the most foul cases of bad oxidation
I ever have seen was for a Barolo. It would have been a text book
example of what bad oxidation is about. It stank so much that I flushed
it down the toilet. Yquem, higher grades of Tokaji, and some top BA and
TBA Rieslings from Germany can withstand considerable oxidation which
adds to their complexity up to a point.

Oxidation is neither black-and-white good or bad. There can be too much
or too little for nearly all wines.

Of course if you wish to make a fruit-juice-like wine that tastes as
much like grape juice as possible, then oxidation must be severely
limited. However the beauty of the classic wine grapes is that they can
produce a wine with a taste and bouquet quite different from that of the
grape juice from which they are made. Very controlled oxiditation is
just one of many factors that help shape the transformation from raw
wine to a polished finished product.

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