All content and photographs copyrighted 1997-2001, all rights reserved. Flash lighting is the most common cause, followed by late afternoon direct sunlight. The result is often an uncomfortably strong orange, yellow, or red look to skin in an otherwise well balanced, natural looking picture.
Some cameras are bigger offenders than others.
This particular shot was the most intense example I've ever encountered. Orange skin tones, looking much like heavy pancake makeup, ruin the picture. After correction, the skin tones are back to normal. The rest of the picture's colors are unaffected by the procedure. Setting the fuzziness to around 20 seems to work the best for most pictures.