Ugh, this has become my favorite music feature of all time. I've made amazing playlists in Spotify by using Shazam around town in cafes and clubs. It was too good to be true.
There are many times when a song suddenly pops up into your head, and you cant record the exact lyrics, the may likely be a few words that is wrong so Google doesn't help, and humming it in Shazam never worked. I had always thought my voice was sounded too bad.