>>3245979I think she being her dominate self would spit because swallowing seems submissive.
However the situation can only arise because she allows it, the guy probably tied up and only in a position to receive and not give. If she were blowing to the point of climax, she is more than capable of getting out of the way in time.
So...swallow, but only when she desires to. I don't think there would be a situation for it to be accidental and fir her to need to spit in surprise or disgust or something.