How clean is your house?

I've just watched possibly the worst ever episode of this excellent Channel 4 series - this guy in Wareham had fifteen years of crapola in his house, about a gazillion house and fruit flies, a cheesy toilet, enough crumbs in his bed to feed an army and every strain of bacteria known to man.

I now feel totally okay about having a slightly stained worktop that no amount of scrubbing will get rid of and dust bunnies under my bed. It does, however, make me worry about the dirt and germs that you can't see. This guy (who is incidently now looking for lurve now) shared his bed with lots of bacteria - they showed him what it looked like magnified like a million times. I could have sworn that I saw a bed bug in there (the size of a small horse under magnification) but David said that I was letting my imagination run riot again. Still. Tomorrow I'm going to Dyson all the mattresses, sterilise my entire kitchen and bathroom and de-flea the dogs.....even though they don't need it.

Question: how dirty does a house have to be to warrant a visit by Kim and Aggie?