I was putting 3-4 TBSP's of PBW in my fermenters, then filling with water to the top of the krausen line. Soaked for a couple days till all the crud fell off. Not much smell left. Well, I got tired of waiting, maybe the cleaner soaking into the plastic ( none so far), so I switched the process.
I pour an 5qt ice cream pail of water in it & swish it around to dump the yeast I'm not washing down the head. Then take it outside & fire up the garden hose. I set it for a spray that's about 3-4" wide at no more than 12" distance. Then hose all the crud outta the inside that way. Dump that & repeat till clean. Then Remove the spigot & soak it in PBW to loosen the crud inside it. I use a set of 3 aquarium filter lift tube brushes to clean inside the spigot & spout. Also to brush the seals & lock lug. Then rinse well. I use a soft cloth soaked in Starsan to wipe down the bucket & the spigot mounting hole. Dip the spigot & parts in Starsan & re-assemble wet. I hit it with Starsan again right before filling...no smell after that.