If you have a smelly closet and
1) you have tried using a deodorizor, without success; and
2) you have looked for hidden stinky shoes, but there aren't any; and
3) you have tried leaving the closet door open, but it doesn't help
then you might want to investigate the possibility that the culprit (i.e.possessor of the clothes in the closet) is actually hanging up their clothes at the end of the day instead of putting them in the hamper. Upon further inspection, you may find seventeen (that's 17) soiled shirts on hangers that are overpowering your feeble attempts to expel the unpleasant odor.
One load of laundry, one more problem solved.