@reosarevok, could we eventually get rid of the following guideline?
https://wiki.musicbrainz.org/How_to_Identify_Labels
It was entirely written pre-NGS, when it was not possible to have more than one label on one release event.
So it is really oriented to how to eliminate all non-primary labels to keep only one.
I think now is preferable to include all logos (except hairdressers, series, etc.) in the label fields, to make a clear disambiguation between editions.
Related to:
Who said every logo is a label? MB ain’t no Discogs.
Other than that… oh well.
It is a pity we can’t have images attached to labels. This would take many of these puzzles away. I often have to go look on Discogs to work out which is a label logo and which is just an advert logo.
Err… yeah… they get pretty weird with what they think is a label.
I think the “label” appellation is problematic because it can mean several things in english.
A label can mean… (according to Wikipedia)
The term “record label”, derives from the circular label in the center of a vinyl record which prominently displays the manufacturer’s name, along with other information.
That’s the broad definition.
Another definition is a label is a record label.
That other definition requires a better understanding of each company’s role in the music industry and is not simple to determine in every cases for the end-user/editor.
Since NGS, there was never a consensus (to my knowledge) on which definition to use. However, I know it was decided once (during a MetaBrainz summit I believe) to move distributors out of the label entities eventually (STYLE-466). I agree that the guidelines should be updated or clarified.
Yup! And guess what, we have a ticket MBS-4683 on that.
UI could help a little bit here.
For instance, if we could differentiate imprints and holding companies at the label entity level, then the “label” field when editing could be changed to something like “label/company logos”. And the system can then automatically treat imprints and holding groups differently in the release display or in the editor once selected.
Obviously it would not be that simple. Just a quick thought to further flavour this complex thought stew 
I mean of course:
But many releases have several logos/labels/imprints (I am not English), even sometimes on the spine itself.
This guideline dates from a time when we could not reflect the release reality of having several labels.
This guideline was based on a hard limitation of MB, that has since been lifted in 2011, with NGS.
When I read this guideline, I don’t think it helps anything now.
I mean it’s obvious that a distributor, if you know it’s a distributor, should use its specific relationship. As well obvious for series that have their own stuff, and non-music-related logos that should not be used.