I am disappointed with the number of MP3 files I get that have synch errors in them. These result in annoying clicks and gaps in the song and make listening to it a pain.
I am going though my collection and am trying to replace them with good copies.
I use Foobar as my music player and it alters you to files with synch errors, I also use the program called MP3 Utility which runs through a whole folder and alters you to those files with synch errors.
If we all started doing this we would tidy up all the files out there !