Apparently, dangersense potion can’t highlight echo coated traps BUT they still leave the small glint

I noticed it months ago so I had to check just to be sure if echo coated traps are truly visible without needing anything to reveal echo coated traps. Turns out you CAN still see the echo coated traps in this way. It's just barely visible but you can take advantage on this one when you make traps in multiplayer worlds or servers.