From a perspective of person who is (pro)actively looking for more work, freelancer.com is full of projects along the veins of "write me some software". It does not make sense to even bother applying to projects like that, as the time spent writing an application letter exceeds potential income.
~6 years ago I did a fair number of small projects on rentacoder.com - the quality of average project description was much higher (did they do any vetting on incoming projects?).
odesk.com on the other hand has a lot more projects whose authors understand a thing or two about how software development works (i.e. reasonable project description among other things).