Part of the problem is one person's Skilled Play is another person's metagaming. For example, I (the player) knows acid and fire will work on trolls, brown mold exploded with fire, a bugbear isn't a fair fight for a 1st level PC, and never drink the fairy water. But does my PC? Is it skilled play to know the DM would put a secret door at the end of a "dead end" hall? Is it fine to use genre savviness, knowledge of the rules (including knowledge of monster stats) and Meta-game thinking to outwit the DM?