Kitilark62 If you have Cats and Dogs, that pack has robotic vacuums, 2 of them in fact, one cheap and the other more expensive. So, if you have that pack, buy one for each floor level in your house and place them somewhere where you have enough space, 1 per floor level. If you have more than one building on the lot, you still only need one for each level. You don't need to place them in every building, just one. Upgrade them, turn them on and set them to clean on any of the frequencies available using the options on the base. You don't have to upgrade them but one of the upgrade options is incinerate. If you upgrade that option, then you won't have to send a sim to empty them as they will automatically empty themselves. You do have to keep an eye on them though as they will break from time to time and can make a big mess when broken. If the floor level already has dust piles and bunnies or fiends, you'll need to have a sim pick up the dust piles and stomp on the bunnies if you want to clean up the lot quickly but those will also disappear over time after the robovacs have been running a while so it's not strictly necessary. When you need a level to get dirty to complete either BTD aspiration milestones, just turn one off and let the level get dirty. After the sims have completed those milestones, then turn them back on. Using the robovacs will keep the level clean, including porches and other areas where you can't use the vacuums you have in a sim's inventory. The BTB vacuums do require about a two tile clearance to work so, using the robovacs will get you around that as they can clean spaces that a sim with a vacuum can't.
Hope this helps.