Vincent, please.  Vinny makes him sound like one of Joe Pesci's understudies.<br/><br/>I'm not sure Slytherin would turn down a sufficiently evil, nasty, and motiviated candidate regardless of heritage...particularly if the muggle-born in question was willing to play ball on the subject.  Why deny the use of a valuable tool?<br/><br/>There may even be a secret doctrine or two in the House, to the effect of 'here's what we tell everyone else we think, and this is what we're actually up to'.