From what I've seen, there should be two classifications of neutral alliances:
Type I neutrals: Conventional, usually paperless alliances without any treaty web muck. Much simpler for Pre. (e.g. GPA)
Type II neutrals (pseudoneutrals?): Alliances with treaties all over the place with multiple different spheres, and no allegiance to any sphere. They presumably give Pre an headache (e.g. Pantheon, NPO)