I guess so...that and any food left on the bottom...I have seen them clean the bottom of the net. as for "poo" on the bottom of the net, there is none there. So u can come up with ur own conculsions...lol
As for them eating feces, that's not true. They live off algae and worms, for the most part. Therefore they should be fed algae disks and shrimp pellets.
The feces will stay in the net, so get a turkey baster to remove it.