on the Crank page, http://bvs.wikidot.com/the-crank
there are two errors in the Crank Requirement list,
another wiki page, http://bvs.wikidot.com/guide:r00t confirms these corrections.
As for actual experience, I just acquired Filthy and Noodle Shop with only a crank of +2.
Corrections are in brackets:
Find Errant Bit on Syntax Error Item Crank 1+
Find Dance Floor on Mind The Gap Key Crank 2+ (recommended, not required)
Find Delicious on Eat The Tasty Key Crank 2+ (recommended, not required)
Find Chosen on Flaw in the World (Nin) Key Crank 6+
Find Filthy on Flaw in the World (Tai Nin) Key Crank 6+ (+2 recommended, not required)
Find Hopeless on Flaw in the World (Gen) Key Crank 6+
Find Noodle Shop on Flaw in the World (Gen Tai) Key Crank 4+ (+2 recommended, not required)