My three are on fleece (with newspaper underneath) and I clean them out every day. I change the fleece and remove any wet newspaper. It only takes about 10 minutes so isn't a huge chore. When I say 10 minutes, I'm not including the time I spend playing with the pigs or talking to them in a stupid voice.....anyhow, back to the point.... I find there isn't a problem with a wee/nasty odour, just sometimes a 'guinea pig smell' and this is normally in the morning when there is a day's build up of wee/veg/hay etc. They are also in the 'dining room' where there isn't much other house traffic or smells created, but in a normal living room, I'd imagine the air moves a bit more!