Well (a lot of experience on that "field" here), ans answer is NO and YES... Actaully most of free and paid sites "don't work" due to various reasons like fake profiles, too many inactive members, too many women there, etc,etc. But if you find nice sources, which are updated on reuglar base like
Hookup Sites (some bloggers) or adult dating by user votes, then chances are much much better that you will get laid very fast It took years for me to "learn how stuffs work"...