What fandom?! Seriously the show hasn't started yet. What happens if it comes on and it's complete shit? Some of the smart ass comments were funny, yours gave me a chuckle. But insults? People like that can fuck off. I'm expressing my opinion and tagging as I please. I get that it's not always going to be a popular opinion but people get to make the decision how they respond to it, they get to decide to poke fun, or be a complete asshole.
"What fandom"? Seriously? Have you not looked at the Elementary tag like, at all? (Though if you having it wouldn't surprise me, haters rarely check out the tag they post hate too.) Who cares if it hasn't started yet? A large group of people in our fandom (and seriously fuck that noise, we became a fandom the instant we started talking about the show, developing headcanons, raving in our tag about how excited we are, and generally acting like a fandom) have seen the pilot (those lucky bitches (and I say that lovingly) who got to see the Elementary panel at comic con) and the general consensus is it was amazing. So don't 'what fandom' me like you don't already know what fandom came down on your head. We are Elementary. We are legion. We are- oops wrong show. >.>
As to your point about tagging? Do you understand how tagging works at all? Here are the general rules: First, don't tag your hate. Second, if you do decide to tag your hate (because really, there's nothing that can stop you) at least have the stones to accept the consequences. Because people track tags who enjoy or even love whatever the tag is, especially fandoms. So if you don't want your hate to fly back in your face tenfold (seriously man, karma's a bitch) don't tag it. It's that simple.
Also, tagging your hate is an asshole move. You were an asshole first, you shouldn't expect the rest of the fandom to be as cuddly as smartasses like me. (Ok, stole that line from Jayne, so sue me.)