Everyone thinks they know Los Angeles.

You don't need to stand on its hot smoggy streets to feel you've been there because it's quintessential America, isn't it? Sun and the freeway, palm trees and movies, thin people and mad people. We all know it from film and TV.

But if you speak to anyone who has lived in the States, or even just visited that country, they'll shudder and tell you that America is nothing like it. LA is a strange and frightening world of its own.

This is probably why Louis Theroux has chosen to go there. His new documentary series, LA Stories, is a succession of films looking at the odd and the brutal in the infamous City of Angels. He even moved his family across the Atlantic to live in the city so he could truly be immersed in the place.

'Tip the world over on its side and everything loose will land in Los Angeles, said Frank Lloyd Wright so, really, there is nowhere better for Louis Theroux to go given that he specialises in teasing out the truth of the freaks, having them blurt it all onto camera whilst he stands gently to one side.

So when I learned this first programme was about dogs I was surprised. He can't be aiming for the weird if he's filming in a dog pound where rejected pups huddle in cardboard boxes? This is sad, not bizarre.

LA has millions of dogs, many of them running filthy and wild on the street. Of all the countless thousands who are beaten, kicked, abandoned and neglected, a tiny proportion end up in the cages and boxes of the pound.

The main role of the exhausted staff is not to feed them and clean them and teach them good animal behaviours, but just to decide 'who gets to die today?' There is simply never enough room to keep and shelter the constant flow of unwanted dogs and employee Leslie tells Louis that many of her colleagues are on anti-depressants. Every day in work, as soon as her jacket is on the peg, she must address herself to the question of which dogs will die today.

Mercifully, some of the dogs are re-homed instead of injected. Louis meets Max and Nancy, a trendy, weird, New Age LA couple. They rescued Caspar, a pit bull, from the pound and took him home to their pure white apartment then seemingly got distressed when he, like, upset the feng shui.

'It was an emotional experience,' nods the dipsy Nancy when revealing Caspar mangled her ankle. The dog seemed to have deep problems, probably springing from the brutal life he'd had on the streets, and needed careful and specific attention so, naturally, his hippy owners called in a Zen dog trainer. Needless to say, Caspar was soon put down.

The stories of squalor, neglect and abandonment were hard-hitting but I felt Louis was wasted on the relatively soft subject of dogs.

He is at his best when up against freaks, not animals. Louis excels as the calm Brit the weirdos can bounce their madness off. He'll ask a clever but devilish question then lapse into his persona of perplexed nerd and let the grotesque slide effortlessly to the surface like oil on water.

No-one can forget his incredible programme with the hideous Jimmy Savile where he almost seems invisible on camera. He is the quiet, polite and bespectacled boy standing next to the garish Savile, who is glowing in a crispy shellsuit, his limp white hair and cigar smoke trailing a streak behind him as he parades around his bachelor pad, showing off his exercise bike and his dead mother's dresses.

Louis Theroux excels at quietly bringing these people to the fore, so that we almost forget he is there, quietly prompting and questioning and eking out the uncomfortable truth.

This art seemed squandered on wee dugs, though next week he turns the searchlight of his attention onto the notorious American healthcare system, and goes inside the famous Cedars Sinai hospital. I'll definitely be watching.