The best place to find freelance workers is by asking the people you know.... Word of mouth is generally the optimal method to finding quality workers/vendors in any field.
I never look online or in the yellow pages for contractors to work on my home.. I ask homeowners I know who they use. The same is true for any profession.
The primary issue for both clients and workers on freelance sites is that everyone is a username and 8bit ASCii text does not convey tone or inflection. So read all the reviews you want, you'll be hard pressed to tell if someone is being sarcastic at times. Or even if the review is legitimate in some cases. I find, online it's much easier for unscrupulous people to appear legitimate.
If no one I knew had any recommendations, I'd be first shopping locally for workers that I could meet in person. Face to face will tell you a lot more about someone than anything online ever will. Heck, even a phone call is better at conveying dedication, interest, and experience.
Also be aware, that many successful freelancers never bother with online middleman sites and forfeiting commissions; Such sites aren't really necessary if you've built a stable of reliable, return, clients. So you'll never see these types of workers at online sites.
In the end.... everything is just a roll of the dice regardless of what you use to find people. Sometimes you get lucky, sometimes you don't. And that's true for any business relationship. Your guess is as good as anyone else's. You'll find freelancers that state www.example.com is the best thing since sliced bread... and you'll find others that think only rip-off clients use www.example.com.