Quote Originally Posted by dsaxton
What's the confusion? If someone has a set, you're drawing dead to a flush.
The confusion is that you're not drawing dead. Nothing about someone having a set removes the spades from the deck, so you're very much drawing live (not to mention the runner runner thing mentioned elsewhere).

Drawing tends to imply that you're not currently the winning hand, so not being ahead on the hand doesn't mean that you're drawing dead.