I heard this from another DM who had problems with his party using rope trick to hide and get their 8 hours sleep and new spells per day. What he did, was when the party was in the BBEG's castle and decided to rope trick sleep after burning a lot of spells, the DM had the BBEG send out his minions to sweep the castle with detect magic (would you not search your castle for intruders after hearing that half your defenders have been taken out?). After finding the aura of the rope trick, he stationed a large force of guards outside it, much to the surprise of the players when they woke up 8 hours later.
I also heard a great solution to hostage scenario problems. This DM had a problem with his players not caring about the fact that the hostage-takers were going to kill the hostages after a certain amount of time, confident that they could simply cast raise dead on the dead people afterward. The DM, rather annoyed at his player's nonchalance, had the hostage takers eliminate the hostages by casting flesh to stone on them, then rock to mud, followed by bless food and drink. Thus the party couldn't cast raise dead because there was no body. For that matter, they couldn't cast true resurrection either because the hostages weren't dead, merely transmuted to water form instead (which has by then probably evaporated). I thought that was golden genius.