No side brush means dust stays in the corners

A robot vacuum without a side brush will push dust along baseboards and into corners instead of pulling it in — which kind of defeats the purpose of an automated cleaner. Side brushes are the cheap little plastic arms that flick debris into the suction path, and skipping them means fur and crumbs build up exactly where you don’t want them. If you have pets or baseboards that collect dust, a side brush isn’t optional — it’s the difference between clean-looking floors and actually clean floors.