I think the only thing I've seen is that there should be at least some notoriety to the bootlegs. Like that it's a bootleg that's been circulating around in fan communities or a batch of fake CDs sold in some shady market or a leaked version of an upcoming album shared on P2P. Something that makes it beyond just a thing between a couple of people.
I think if you read through the MusicBrainz about page, it makes a lot more sense:
>As an encyclopedia and as a community, MusicBrainz exists only to collect as much information about music as we can. We do not discriminate or prefer one "type" of music over another, and we try to collect information about as many different types of music as possible. Whether it is published or unpublished, popular or fringe, western or non-western, human or non-human — we want it all in MusicBrainz.
I think if you read through the MusicBrainz about page, it makes a lot more sense:
>As an encyclopedia and as a community, MusicBrainz exists only to collect as much information about music as we can. We do not discriminate or prefer one "type" of music over another, and we try to collect information about as many different types of music as possible. Whether it is published or unpublished, popular or fringe, western or non-western, human or non-human — we want it all in MusicBrainz.