This actually annoyed the heck out of a DM of mine once. We entered a room where there was writing on an archway. Once someone said they were looking around for traps/enemies, he chortled and said "Explosive Runes!".
To which I replied, "but DM, you said before we can't read anything if we're using infravision. Nobody has a light source lit at the moment."
I mean, eventually someone did get hit by the Runes when we decided we wanted to examine the writing, but the look on his face made me wish I had a camera on hand!