I've tried to summarize the process of dropping (and reaching the decision to drop) a package from Factory here: http://en.opensuse.org/openSUSE:Factory_drop_policy
There is also a small howto so people know how to drop the package (and restore it if needed).
As there is no strict rule or exact step-by-step way to decide if a package should be dropped, the "policy" described there is rather fuzzy. I don't think it's an issue, but if people this is not good enough, we can improve things.
Is there anything missing on that page? Or does it look good?