Why are some iTunes Store songs marked as CLEAN when no EXPLICIT version exists?

I have downloaded a number of items from the iTunes store which are marked as CLEAN. I understand this is common in tracks (I'm looking at you, rappers!) where an EXPLICIT song has has the swear words removed or bleeped or reversed etc. However, the tracks I have are the original recordings, and are not clean versions of tracks that were originally explicit:

What makes iTunes decide to add these flags to certain songs, and what is the point of a CLEAN tag?

In the example given every track is marked as clean, but I have seen it on individual songs also.

Solution 1:

I just had a look at differently tagged files.

The responsible ID3-tag is rtng (short for rating). If set to 1 the song will be marked as EXPLICIT, while 2 shows up as CLEAN. Every other value leads to no label.

I recommend Kid3 as a tag editor.

EDIT: According to this and this, the values should be 2 (CLEAN) and 4 (EXPLICIT). I can't reproduce those, maybe someone copied it wrong...

Solution 2:

This is a hypothesis, but I expect it's because those songs have been explicitly (no pun intended) listened to by iTunes staff to make sure there aren't swears or R references. Another possibility is that artists, when submitting content to the Store, have the ability to flag them this way, and often do so even when no explicit version exists.