A few robot vacuum cleaners also offer a mopping feature, squirting water out onto the floor, then using a microfibre cloth to wipe up dirt. These can be a great option on hard floors, where trodden-in dirt stains tend to stand out more. We find ours useful for keeping a relatively light kitchen floor clean after cats have walked on it. The downside is that with the mop attached, you can’t vacuum carpets. So, if you’ve got lots of hard floors, look for a model with a mop for cleaning; if you’ve mostly got carpet, then the mopping feature probably won’t be a lot of use.