FWIW.....
"The presence of pathogens [disease causing organisms] in food usually cannot be detected by sight or smell..."
Source: " FOOD SAFETY HAZARDS AND CONTROLS FOR THE HOME FOOD PREPARER" http://www.hi-tm.com/homeprep/Home-2006-2col-forpdf.pdf
There's lots of great food safety information on Dr. O. Peter "Pete" Snyder's website: http://www.hi-tm.com/