There’s nothing I find funnier on Sherlock than the fact that Anderson imagines Sherlock as being this suave, sexy, cool bamf who catwalks around kissing girls. When in reality he’s an adorable little gay sweetheart who folds napkins, blows things up by mistake, flails around, and glues pictures of John’s head to things.
Well, it starts off with John alone until he finds Sherlock. They solve crimes together and John moves in after killing some dude with teeth. John gets wrapped in explosives by Moriarty and Sherlock freaks out a lotta bit. The Woman tries to bang Sherlock. Sherlock doesn’t bang The Woman. Sherlock jumps off a building and breaks John’s heart. Sherlock comes back from the dead wanting to bang John, but he can’t because John’s banging an assassin he doesn’t know is an assassin. Go figure. The assassin assassinates Sherlock and he goes to his Mind Palace that’s a shrine to his love for all things John and comes back from the dead, like, again but for real this time. He kills Hannibal’s brother for John. Moriarty was fake dead, too. John still doesn’t bang Sherlock.
meta: The man in the mirror: Sherlock’s other self.
John calls Mycroft for help in His Last Vow, after finding Sherlock’s been using again, sleeping rough in a drug den (possibly to avoid sex with his faux girlfriend Janine). Mycroft’s first words to Sherlock:
"The siren call of old habits. How very like Uncle Rudy – though, in many ways, cross-dressing would have been a wiser path for you."
The very particular framing of Sherlock’s reflection in the mirror, as Sherlock reacts to his brother’s seemingly venomous remark by not responding to it in any way, is telling. It is symbolic. The mirror seems to tell us there that Sherlock has another self-image, or even another self. Moments later, Sherlock is furious with Mycroft and actually assaults him for trying to warn him off the CAM case. But this snide remark about cross-dressing is met with silence.
Why, of all the things he could say on the presumably alarming - if too-familiar— occasion of finding his little brother “back on the sauce,” does Mycroft say this, exactly? Perhaps Uncle Rudy was also a cross-dresser, or another family drunk/drug abuser.
But to my mind, Mycroft is saying that if Sherlock had been true to himself (“the wiser path”), perhaps John wouldn’t have ended up with Mary, and Sherlock wouldn’t be trying to nurse his broken heart by turning back to drugs (even if John is only part of the reason Sherlock did it.)
Posit: Sherlock is only wearing the sheet to Skype. He usually wears nothing around the house.
Sherlock walks around the house wearing only a sheet, potentially maybe even less.
Sherlock often doesn’t seem to notice whether John is actually around or not.
If you were prone to bouts of partial or full nudity that you didn’t want anyone to witness, you’d pay more attention to the location of your “flatmate” to prevent embarrassing mishaps.
I infer from this that Sherlock walks around in this state whether John is in the room or not.
If you’re going to be so obvious, then why not say that Sherlock walks around naked all the time? Pff.
I’ll go a little further with the observations, if I may:
Observation #1: At the point we enter the conversation, Sherlock already has his laptop open in the kitchen and has made himself a cup of tea or coffee. Inference: he was already talking to John via Skype before temporarily going back into the bedroom.
Observation #2: When he comes out of the bedroom he has nothing in his hands - nothing that he might have been going back to retrieve. Also, John feels embarrassed. He must have gone back into the bedroom to cover himself up with a sheet, then, probably at John’s request.
Observation #3: It doesn’t seem too early in the day and yet Sherlock seems sleepy. Obviously he was up rather late, then. (That drink is probably coffee not tea).
Observation #4: John was in Dublin the previous day. Since he’s somewhere rural now and it’s probably still morning (unless Sherlock was up really late) it seems unlikely he’s been back to London yet.
Conclusion: Sherlock had the laptop in the bedroom with him (no doubt because he was talking to John in Dublin late into the night after going to bed). His sleep was interrupted by news about a new case - on learning where the crime scene was he contacted John to send him to the location. He then went back to sleep, then once John was at the scene he woke Sherlock up again via Skype. Sherlock, needing coffee, got up without bothering to dress, carried Skype-John into the kitchen, talked to him while strutting about naked making coffee before finally giving in to John’s pleas that he go and cover himself up. Because late at night is one thing, but mid-morning on a crime scene with a bunch of police officers looking over your shoulder at your naked flatmate is another.