How do you indenfity a trap chest?

Question

How can you tell if a chest is a mimic?

Answer 1

You can tell if a chest is a mimic by looking at it, you don't need to actually hit it (although that works just as well). Mimics actually have a lock on the chest, where real chests do not. I didn't take a picture, but I believe it is the same for metal chests.

Answer 2

Mimics can be countered in a multitude of ways. One way to tell the difference between a wooden chest and a Mimic is to look at the front. If there is a lock, do not open it. If there's none, then it's a normal chest (but may still be rigged with a trap). It is also possible to see the Mimic's teeth underneath the lid, which is slightly open, as opposed to the fully closed lid of a normal chest.

Likewise, there are differences between a normal iron chest and a Mimic which make them easier to tell apart. A Mimic disguised as an iron chest has a slightly clearer color scheme in comparison, and portrays two white vertical hinges on the front, one on each side.

From The Dark Souls Wikia