It seems that users taking advantage of Google Music's new scan and match feature aren't always getting exactly what they expected added to their music libraries. The new feature, which launched in the U.S. just a week ago, lets users bypass uploading of new music by instead "matching" the music on the user's computer with the same file in Google Music automatically. That's all fine and dandy if it works, but users are reporting that songs with explicit lyrics are having the clean versions of songs added instead. This doesn't come as a complete surprise considering the same reports came out when iTunes started its own matching service, but this still shouldn't be happening.
Whether its because of a licensing shortcoming or technical issue with identifying music, we hope that Google can get this one figured out. Users with explicit music usually have it for a reason, and don't really want it replaced erroneously because a service isn't operating properly.
Source: Droid Life