I've done a little bit of work on Freelancer, and I did some work on RaC years ago - you just have to pick carefully. With the low-quality projects, there's also alot of low-quality developers, who copy and paste the same response to every project (are are often front accounts for development sweat shops). If you're in the same area as the project owner, and can write up a decent proposal (meaning you spent 2 minutes reading the project description and 5 minutes writing why you're best) you can win a large amount of work.

There are alot of projects where you can tell the project owner is "just outsourcing it" and thinks they'll get $25,000 of dev for $250. The overall volume is high enough, however, that you can find some quality gigs.

What I do have a problem with is nickle-and-diming the site does, especially with regard to their "tests". For instance, the ColdFusion test is probably 8 years old, and pretty embarrassing. (and despite some attitudes to the contrary, the language is quite current) Even "modern" tests like the HTML 5 test seem off with regard to content covered. They almost seems as if they were written using $25 contractors off the site.