I am not sure if is true that, with sati present (a sobhana cetasika), mind really defiles when, for example, issa (a asobhana cetasika) would arise. If sati is really firm established, i belief, it is possible that mind does not really defile, in the sense, it does not really become jalous when issa arises.
Unless one graspes at arising defilements, and gets involved in them by way of identification, attached to them, i belief arising defilements do not have to defile mind. If one looks at those arising mental phenomena with wisdom (‘this is not mine, not who i am, not myself’) then mind does not defile.
Siebe