I have to say, reading this particular topic reminds me of intense discussions in college where you debate the meaning intended by writers (or in this case ALL the creatives who decide on the little details).  I suspect there is seldom a "throw away" decision where it's "whatever is in the closet" at the moment.   I inagine the creator (Andrew Marlowe in this case) has the "giant vision" and the individual writers/directors of a particular episode run by him with their colors/clothing/coffee usage/etc.  It is Marlowe who likely insures the continuity and inuendo intended for the particular scene/show.  By that I mean there is a level of coordination in every aspect and every detail that goes into any scene and any particular episode.  What they all intend and what we all come away with are likely different to a degree; however, the more you watch anything with an eye on the details (or read a book or view an art piece with the details in mind) the more likely you are to gain the additional level of subtlety intended in the episode.  For example, as someone who works with music (non-professionally), I know that not only are the lyrics important in the selected songs, but the melody/harmony/rhythms and instrumentation…all with a single goal in mind (to set the stage and mood of the audience).  The same is true of the costuming (right down to the colors, length, style, etc).  In fact, the same is true of the acting itself.  The subtleties that Stana, Nathan and others use to convey their characters are not accidents. 

So, it's all about setting the mood and background to support the story being told.  The more facets of the story (the details, in other words) that are well coordinated and that can convey the mood and tone and intentions of the characters, the more realistic the story seems and the more in tune the viewers are with the intentions of the writers/directors/actors. 

And, gang, I LOVE the fact that so many of you are catching the subtleties.  Makes me think Castle watchers are a "tad above" ordinary viewers in their understanding.  Makes me love being a part of this group.