Glad you asked...
When beef is spoiled it usually turns colors and has an awful smell. It will usually turn a brown and green color. It will smell like something died.
Then again, this answer might help you...
The best way to tell if beef is spoiled if by the smell. If the beef smells foul in any way, do not eat it. You can also tell by the color. If it appears "off color" or has visible mold, do not eat it. The best way to ensure your beef is not spoiled to to use it or freeze it by the "sell by" date on the package. For more information look here: http://community.cookinglight.com/archiv...;

