When does Google think sites are affiliated?

Reciprocal links?

[brmmbrmm]

I run quite a few sites which are all on one IP, and am planning to submit them all to a directory which wants reciprocal links. I'm concerned however that the Google hilltop algorithm will think that I am then affiliated with the directory and devalue the inbound links. Am I being over cautious? I read that if A->B and B->C and C->A then Google thinks you are affiliated. If someone can clarify this I'd be very grateful.

[dirkz]

Of course all your sites listed in the directory will be affiliated with each other.

But they already are because they share the same IP.

[bakedjake]

Sometimes hitting the "related sites" link can give you a pretty good idea.

But take it for what it is - sometimes it's way off the mark.