Just my take on riddled maggots. Fresh maggots need to be riddled if you don't know the shop you are buying from, shops owned by top matchmen sell top class bait.
Skins need taking off, dead maggots are brilliant baits, manky old skins and old black maggots need removing.
Clean maggots are paramount, clean to me means a simple riddle not anything other than that. Shifting the dead skins and turned maggots are the equivalent of wire brush and Detol to me.
I have a stainless steel bar shaped in a soap fashion and odours of baits are soon removed, it's about 25yrs old, still works mighty fine.
Edit
Removed skins are dumped in the grass by the side of my peg.