What i wanna know is......

More than half of the files (not including mp3 or audio) on like bearshare are not the actuall program they say they are, but instead a virus or sometimes porn(in most cases for videos). Now wat i wanna know is why would some1 put up viruses and name them something else and say on the title they work 100% fine. Its not hard to recognize when you see GTA Vice City on bearshare and says 202,477 bytes. Which i see like thousands of files with 202,477 bytes, also anyone know who started hat virus(i dont wanna download it to see).