Christians had incidental knowledge of mosque cleanliness but were barred from worship.

Evidence

Friar Simon remarked how ‘cleanly and really reverently’ mosques were kept. The Liber Nicholay certainly expresses the local knowledge of Christians in places where Islam was practised, when — with surprise at something superfluous? — it describes how there is no spitting in mosques, so that of necessity people must go outside. — Norman Daniel, Islam and the West, 1201