Mike said:
Also, there are folks that just troll round You tube looking for songs to lodge claims against just to try their luck, especially it seems if there is any clue that the song may use pre-recorded material like Sound loops Realtracks, etc.
Bob Dylan has a vast array of lawyers constantly on the lookout for infringements. What cost fame and talent? In fact, the copyright holder is OBLIGATED to pursue infringers or risk losing his/her rights.
Few of us can afford a team of lawyers.
On a similar note; I once talked to a patent attorney about an invention I had and he said that if the infringement didn't total in the thousands of US Dollars, attorneys wouldn't go near it.