Does the NEC allow Romex to be run across the bottoms of floor joists in crawl spaces?

This is something I see done all the time, and I thought it was legit because of the accessibility of these places, and I see it pass on inspected new construction. But I can't find any article allowing it or exempting crawlspaces from 300.4.

Maybe everyone (rightfully) assumes that no inspector in their right mind is going into that crawl space to enforce this...?

-John

[This message has been edited by BigJohn (edited 08-12-2005).]