Except if there was no indication whatsoever that they would treat the eponymous vase differently, it's obvious they're acting on meta-game knowledge. Something I ask them to try to avoid. Besides if I ask how they break it, then I have to ask how they break everything and that leads to a slower game which is what I want to avoid. I'd rather have fast-paced action and move the game along than face some hypothetical "wrong" DM style. I don't remember the last time it happened, but I may tell someone that no, they don't change PC behavior because of what I said as DM that wasn't part of the description of the world.My perspective on that matter is, just because information might cause you to act a certain way, doesn’t mean you couldn’t act that way without that information. For all I know, the player would have poked the vase with a 10-foot poll anyway, and if I forbid them from doing so because asking them how they try to break it may have influenced their decision doesn’t seem fair of me. Better to get around the whole issue by asking the player to say how they try to break it first.
But I also run an event based game, not location based. I find dungeon crawls boring most of the time, it's a different emphasis on what's important.