So the returns are in, with the majority of voters (all 5 of you, thanks mum & dad!) considering themselves 'Good' DM's... which is fine, as there's plenty of room for improvement and you'll all keep reading the blog! /cheer
Our new survey is a trickier one: at what point do you consider your PC's to have defeated an enemy... to the point that they have earned XP? I know this is a question I wrestle with all the time. Myself, I like most opponents to choose the better part of valor and peg it rather than throw their lives away for the sake of whittling away two of the Sorcerer's magic missiles before the fourth encounter of the day... but I know for a fact that it can be irritating to never actually get to kill the guy who's been Sneak Attacking you for the last four rounds. Players, in my experience, can tend to feel a little cheated of victory if a villain escapes the field of combat while his less interesting minions cover the retreat.
For climactic encounters, it's an exceptionally bad idea in my opinion to deny the PC's the pleasure of looting a powerful, Evilly-aligned corpse. Recurring villains can be great fun, but if they are to recur, they shouldn't become the major obstacle or opponent in a fight until such time as you, the DM, are prepared for the possibility that they will be killed. And eventually, of course, you should plan for them to be killed. A bad guy who forever escapes justice at the sharp end of the party's weapons will become an annoyance, not a nemesis, so don't tease your players with the possibility of crossing swords with him until his death is an appropriate and realistic possibility. In the meantime, he should have plenty of challenge-level-appropriate subordinates to punt into the fray until such time as the PC's are worth dealing with personally. (Gamers among you, Shodan from the System Shock games is the model of such a villain.)
But I digress. The question is, what constitutes 'overcoming' a monster? Use the comments if you choose the 'Other' option.