Devon's disguise as a human is funny in that it can fool anyone besides Elves. Elves are very aware of the minute differences within their anatomical makeup, so Devon just kind of looks like he's dressing very strangely. The beard baffles them in particular.

We've also decided that Elves in this world have much more complex expressions and body language than other races, with more tiny details and differentiations, allowing them to communicate less with words, or no words at all if they so choose, with other Elves. Because it's a trait unique to their own race, it doesn't really translate to people of other races (and vice versa) and their motives and thoughts are a bit harder to hide from each other.