It could mean it is going through re-fermentation in the bottle or has bacterial problems. As well, old wine will be cloudy if not properly decanted. Most likely this will reveal first the body color and then a rim color. The rim color can range from purple, for a young wine, too ruby, through to russet, then to brown for a mature red. White wines can have a greenish tinge to their rim color when young then change to a deep yellow before aging to a gold.
New oak can also give a golden tint to a young white wine.
These are traces left on the side of a glass when swirled around. This usually is a good indicator of alcohol content or high levels of residual sugar. This is where wine tasting becomes more of an individual art. After swirling the wine in the glass you should start to smell the bouquet with your nose to the glass. Your first smell should be one of caution.