Don't believe it?
Here are some examples that prove they do, but don't click the links unless you take perverse pleasure from (a) feeling sick (b) eating your words...
1. A child rescued in California.
2. A couple prosecuted over animal cruelty.
3. Squatters in Reading.
4. Tenants in a Council house.
There are specialist cleaning companies like this one, who take on the most unpalatable job of cleaning some of these houses, but unless the residents die or ask for help, they are mostly free to continue living like this.
'Diary of an On-Call Girl' is available in some bookstores and online.