If you have to keep tweaking them, it's not passive income. Every time a hub goes idle I move it to Infobarrel, along with about 30 hubs that never went idle but had low traffic.
Since moving them to Infobarrel in the last month, all of my articles have started receiving good, consistent search traffic. One of my best researched hubs kept going idle even though it got about 10 hits a month. After I moved it to IB, I started getting 50 hits a week! From search!
Too many people refuse the face the music. It's not your writing that's necessarily the problem, it's HubPages.