I don't know what I'm doing wrong, but my dubia bin ALWAYS stinks. I recently cleaned it out entirely, got rid of the entire base of frass and put in all new egg crates. That was maybe August or September. It stinks already. Pretty bad. You can be in the same room, but not next to it and easily catch a wiff.
I feed them the same salad stuff I feed Sidney, but even switched to a completely dry diet for a few weeks, with the exception of an apple chunk every other day for water. Didn't help.
Not sure exactly the humidity, but their bin is kept in the house with the lid totally off for air and to not get moisture build up.
I'm going to try a dry roach chow mix and just carrots for water for them for awhile.
Everyone always comment how roaches don't have any smell. Yes. They. Do.
That's very strange. I just went down to the basement to check on my guys and give them some orange and a slice of onion and didn't detect any strong smells (except the onion). The air in my house is pretty dry though. What do you have in place for housing?
Those should be fine too as long as they aren't holding moisture. Do you see any mold on them anywhere? How new are they? It sounds like there may be bacteria building up somewhere in there but I'm not sure where.