That's all well and good if you have the luxury of picking and choosing from multiple offers. Here in the real world (i.e., not in SV), getting a decent offer (if you're not entry level) that's at least equal to your current pay generally takes 6 months - 1 year of hard interviewing. If I demanded a prospective employer scored even 50% on the Joel Test, I'd be perpetually unemployed. Which is probably why employers generally get away with providing sucktastic working environments for software developers.
I find it especially disheartening that the only one of Joel's 12 'tests' that's pretty much a universal 'yes' these days is uses source control.