Apart from sell-by date of course.
I was about to roast a chicken (purchased 1st feb, use-by date 9th feb), but I just opened it and felt slightly uneasy about the smell.
However - I am known for my sometimes slightly irrational food paranoias, so perhaps I am just going mad. I know can't decide if it smells weird or is totally normally.
Any rules to apply in this situation?!