-- John H. Watson, A Study in Scarlet
Most of us, thankfully, will never have the list of issues that got John Watson into the state he describes above when he first met Sherlock Holmes. Almost all of us, however, are going to get hit with a cold virus at some point that puts us in a condition much like that which Watson described at that point.
Getting up at all sorts of ungodly hours, extremely lazy from lack of good sleep, and just crabby enough from all of that to object to rows, maybe not because our nerves are shaken, but mainly because in the state a cold can put us in, we're not taking any crap. (Which can actually be a little useful to the less-assertive among us.)
Finding a certain sympathy for early-Baker-Street Watson is, perhaps, the only bright side to being inflicted with a "blah" head cold. It just has to be endured, and one hopes for a capable room-mate who can leave us alone while perhaps staying just interesting enough to distract us from our minor miseries.
I can understand that firearms enthusiasts like to argue that "a bull pup" was somehow a Victorian way of saying "gun," but the idea that Watson would tell a prospective room-mate, "I keep a gun and I object to rows," seems a little counter-productive. I, for one, certainly would not happily agree to room with somebody that threatening at the get-go. If that was the meaning, Sherlock would have surely looked at Stamford and stated simply: "NEXT!"
"I have another set of vices when I'm well, but those are the principal ones at present," is a lovely and intriguing statement, and truly one that applies to head cold season as well. One would think Holmes might have asked about those, but he had probably made some deductions about those that he wasn't revealing. ("Gambles on horse races, can't remember if he's married or not at a given moment, drinks a bit.")
But, as with Watson's post-war state, the head-cold too will pass. And then back to our adventures with Sherlock Holmes.