Well, the Sleep example would work rather poorly in 4e.
First, you have to hit the barkeep's Will defense. This will only Slow him for the first six seconds (IIRC). Next round, he gets a save. If he succeeds, he's all clear, and only if he fails (45% chance) will he actually fall asleep. And even if he does fall asleep, he gets another save every round, so it's not like the party will have a long time in which to do their snooping.
First, you have to hit the barkeep's Will defense. This will only Slow him for the first six seconds (IIRC). Next round, he gets a save. If he succeeds, he's all clear, and only if he fails (45% chance) will he actually fall asleep. And even if he does fall asleep, he gets another save every round, so it's not like the party will have a long time in which to do their snooping.