Smelling and looking at it is a good way to tell if sealed ground beef is bad. If the beef smells bad, is discolored, or has a strange texture, it is likely bad and should be thrown out.  It is difficult to tell if the beef that has been sealed is bad without opening the package, as the packaging prevents odors from permeating the beef. But, if you are concerned that the beef may be bad, you can open the package and check for signs of spoilage such as mold or a strange smell. If the beef does not look or smell fresh, you should throw it out.