> You might call it "knowledge [and] collected bug fixes," but sometimes the crap is just crap. Key word here is "Sometimes". Reviewing code means you get to

> You might call it "knowledge [and] collected bug fixes," but sometimes the crap is just crap. Key word here is "Sometimes". Reviewing code means you get to find out the reason these hacks were written in the first place, and then decide wheter to keep, rework or delete them. Starting from scratch means you get rid of the worthless crap, yes, but you also lose all the valuable crap.