Hygiene

After a while, Sims start to get dirty, and if they get very dirty, they start sniffing themselves and saying, ‘Ewww!’. Bad hygiene won’t kill a Sim, but it will seriously affect their mood and their social skills – bad hygiene won’t get a Sim promoted at work either. Bad hygiene is a possible blame for Sims dying by satellite. Therefore, it is necessary to take a bath or shower when the Hygiene metre slips into the red – a hot tub also work, but not as well, although it can boost the Social and Fun bars as well. Washing one's hands after going to the bathroom also improves this rating, as does brushing teeth or gussying up in the mirror (The Sims 2). In order to facilitate the latter activities, be sure to have a medicine cabinet, bathroom cabinet or mirror and sink. Sometimes, the shower leaks after a Sim has been in it, so it’s handy to have a mop ready.

In places such as Downtown and Studio Town, there aren't an awful lot of places where Sims can increase their Hygiene. There are sinks with which to wash their hands, and Studio Town has steam baths, but none of them boost Hygiene sufficiently. Therefore, it's best to go out as hygienic as possible. This isn't a problem on the vacation lots in Vacation Island and Bon Voyage because there are baths and showers in the hotels.

In The Sims 3, you can buy the Dirt Defiant Lifetime reward (for 15,000 Lifetime Happiness points), which will make it take longer before your Sim has to take another bath.

Pets
Cats will clean themselves whenever they get dirty, so Hygiene is no problem for them. Dogs, however, will not wash themselves. When a dog starts scratching himself, it's a sure sign that he needs a bath.