I disagree 100%! anyone who has ever picked up an asf knows what direction the flies!!!! ASF's while climbing up any hopper will pee as they hang off the side. LOL! are you sugesting that your hoppers do not get urinated on regularly???!!!! I challenge you to take that sensitive nose of yours and smell one of those hoppers you built after emptying any food.
If they sit on top of the hopper, the top of the tub and any leges are a good foot away from them!!! So how do you figure they would be able to sit and chew on them?
With a proper fitting lid, even babies can NOT get into the hopper!