If it's anything like a lot of the FOAF documents I've seen, it's probably pretty nasty! Even if it's valid RDF and Rosco gives it the thumbs up, there's still plenty of opportunities for stupid mistakes.

Enter Perry Lorier's FOAF Lint tool, this currently has 13 tests to help encourage best practises in FOAF documents, and I'm sure that Perry will be adding more tests as best practises evolve and he gets more feedback.