I think the Ghostbusters and Batman fandoms usually skew a little older, hence some of the built-in homoeroticism.

Perhaps. And this is just like the big actiony manga series, too ~ series full of men as main characters are just going to get a lot of slash. Its the nature of the beast :P So in a way I'm not surprised that a lot of BSC fic is femmeslash, but at the same time...it seems like slashing for the sake of slashing.

*shrug* Different strokes for different folks and all that, I suppose.