Soo . . In SR3, a shaman does not so much summon spirits as he does more call the spirit that is in a specific location to him . .
BGC(BackGroundCount, not BubbleGumCrysis) is generally unaspected, but for example in a Church or on a Cemetery, the Spirit of the place would probably be aspected towards the BGC of the place, even if the Shaman is not . . So what would happen then?
Would you get a REALLY strong spirit in a place with a HIGH BGC as a Shaman?
Or would you NOT get a strong Spirit AT ALL, because the BGC in it's own domain does hamper it?

My understanding (not having the books in front of me) is you would get fewer favors (or none at all) because the shaman doesn't match the aspect of the location. So let's say you have a Petro Voodoo shaman (I know, not a specific totem, but bear with me) summoning in Happy Bunny World. If you applied a background count to HBW, the HBW spirit says "I'm HAPPY - and you're not. So I don't think I'm going to help you."

Hmm, allright, sounds like an idea at least . .