Wine legs, aka
tears, are actually related to a wine's
alcoholic strength, and have nothing to do with a wine's
quality.
The phenomenon of wine tearing was explained in
1855 by a
British physicist and engineer named
James Thompson. Tearing is produced by a complex reaction between the
alcohol and the
water in wine. Pure water or pure alcohol does not form legs. It usually happens in wines, and other
distilled spirits, above 12 percent alcohol.
Anyone doubting that legs are purely dependant on
alcohol content, and not indicative of wine quality, just needs to buy a jug of
cheap California port, pour it in a favorite glass, and watch the
magnificent legs form.