The great extent of their database can be annoying at times. I turned on the TV during the Winter Olympics once, and saw that one of the ice skating events where the competitors skate to music was on--probably Ice Dancing.
The performance being shown was using some fairly well known piece of classical music that I did recognize, so I tried Shazam [1] and it identified it, but not in the way I wanted. Instead of telling me the name of the piece and the composer, it told me who the skaters were, that it was from their Winter Olympics routine, and what round of the competition it was from.
[1] ...I'm not actually sure if it was Shazam. Might have been SoundHound.
OP mentioned that they use the number of customers using Shazam as a metric. Maybe once they decide to use a song in their playlist they (somehow) make sure that it's in the database.
