Ask HN: What is your opinion on freelance websites?

Does anyone have any particularly good/bad experiences to share about using freelance programming sites? How would you rate them? Is it worth to get job from them?

I've heard bad stories stories about people not getting paid, projects never getting finished, etc.. how representative are they?

I'm looking for freelance job that's why I needed to ask this. If anyone is looking for same feel free to visit my page.