I was watching Sherlock tonight and the person I was with said "Oh I wish he wouldn't do that [smoke], Sophie loves him".
I was going to argue that it added to his character and that it was ok because it was portrayed as a vice but I stopped myself. Sophie (not her real name) does love him and so does her sister. They are of an impressionable age and seeing their favourite character smoking on television could influence them a lot.
I'm not saying they are going to take up smoking because of it (although I'm sure it will influence them in some way subconsciously) I think sadly they will lose the respect of Benedict Cumberbatch. Not only is their favourite detective smoking, so is their favourite actor.
When I was younger, I can't remember what age, I found out my brother smoked. I felt horrible. It almost broke my heart. I couldn't understand why my big brother would do something so stupid. I could not see any benefits of it. I don't think Sophie and her sister lead such naive, sheltered lives. I don't think they feel the heartbreak I did but I'm sure they will feel something. A lack of trust maybe? A betrayal?
I remember on twitter a while ago there was a picture of Miranda Hart "smoking" in New York. Her young fans were distraught and demanded an explanation. Miranda tweeted saying that she was holding it for friend. Whether or not this is true doesn't matter, the fact that her young fans believed her is important.
They look up to Miranda, just as Sophie and her sister look up to Benedict/Sherlock. They have a duty (admittedly not one they directly chose) to be role models to their fans. Miranda knew that she shouldn't be known to smoke. I think this same consideration should have been thought about for Sherlock.
I'm not saying there should be no smoking on television, I believe it can add a lot, especially if you are representing society, who themselves are impartial to smoking. I'm saying that writers/producers/actors, whoever need to be aware of their audience. Especially a programme going out before the watershed. If you can't swear before nine, I'm not sure you should smoke (and yes I know the smoking happened after nine).
Having said all this, I do think it adds to Sherlock's character. Is it worth it though?
ps. Does it say something that all of the google images of Sherlock smoking are from tumblr, a predominantly young person's social media? I fear it has already influenced them…