Shakespeare's View of Turning Turk

I thought it was interesting that European Christian viewed Islamic peoples as promiscuous.  The phrase "turning Turk" according to the passage possessed sexual connotation.  Yet, Shakespeare depicts Othello as the opposite.  Othello is the opposite of promiscuous.  Maybe he is making a solid effort to identify with the virtue of the European Christians.  Either way he's in a loving and fruitful marriage in which he remains faithful to Desdemona.  However, his downfall may be Shakespeare's commentary on Othello's background.  Perhaps according to Shakespeare, Othello suffers because this lifestyle is not meant for a Moor. His respectability as a husband did follow the norm for a Turk so it had to be destroyed. This could be really stretching the term but I found it interesting to ponder.