So, I have the "being single" problem and wanted to ask if anyone's tried any Hookup Apps? When I ask if it's good, I am asking if there are not only horny brats inside but some serious boys and girls looking for a relationship. Quite possible such an app should be cross-platform in order to get global enough.

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"...