Ignoring hints is recklessness. The only hint that there is anything off about the room is that the DM says that there isnt anything special about it.

How would carefully examining your surroundings be anything but the opposite of reckless, though. Annoying, perhaps, but that’s a different problem this would only encourage.

Describing things well, putting some thought into world building and just thinking through responses to player questions doesn’t hurt either.

Also, exactly which part of questioning the DM twice and sending a familiar in first was reckless in this scenario?

And don’t even tell me ‘maybe they scrubbed the room after each time.’ Have you ever seen a pizza stone?