I felt a nagging sense of doubt as I ran around the house picking up toys and socks. I knew I would soon get a distress call from our robot vacuum, Gizmo IV, who always gets stuck in the same spot under the couch, no matter how hard I worked. I have to pick hair out of the carpet after Gizmo finishes because he clumps it but never sucks it in. I could see a face full of dust as I emptied its tiny, barely-half-full bin.

I came downstairs the week after pitching the article to find the skid marks on the floors. Our youngest cat, Luna, often poops next to the litter tray. At first, I thought she had gotten sick and had wiped all over the house. The terrible truth was revealed by my nose. The machine was designed to spread poo. I might never recover from the horror. I began to wonder why I got a robot vacuum in the first place, while I was picking up pieces of my cat's feculence.

Maintenance is the art of keeping things running.

More than two decades ago, robot vacuums were expensive and not very good at their job. Features lists have grown and prices have fallen. Around 14 percent of Americans own a robot vacuum, and 13 percent intend to buy one, which would push 30 million into service in American homes.

Raves from friends convinced us to purchase our first robot vacuum. I believe that the ideal robot vacuum owner lives in a single-level home with no pets or children. Our household has one balding cleaner, three messy humans, and two messy cats. King Canute was struggling against the tide.

They didn't tell me how much maintenance they need. It isn't enough to empty the bin. You have to change filters and brushes, remove rollers, clean plastic covers, and polish metal charging contacts. If you don't keep up with regular maintenance, your robot vacuum won't work.

The average life expectancy of a robot vacuum is 10 months. Gizmo I lasted nine before it began to turn uselessly in circles; Gizmo II, a Eufy Robovac 11S, managed eight and then declined to turn on; and Gizmo III, a Trifo Max, made it just six before refusing to hold more than 15 minutes The first to go beyond a full year is Gizmo IV.

No going back.

You may wonder why I persist with a robot vacuum. When you use a labor-saving device, you never go back. A budget robot vacuum saves time. I will never have to clean up another stray Rice Krispie again. It picks up stray cat litter and keeps our hall free of mud and dust.

According to our resident robot vacuum expert, manufacturers have been working on the problems I encountered for a while now. She looked at a botvac that could recognize poop. Ecovacs and iRobot have done a lot with obstacle identification. We have been pushing self-emptying bins.