So, mustache growers of the SDMB, when you undertook your quest:
Did you ever have any doubt that you could grow one?
No… I could probably shave twice a day
When did you realize your attempt(s) were going to fail or succeed?
I shaved it off when I had the sudden realization that I looked like a cop… pretty much the opposite of what I was going for.
Just for the heck of it, how old were you?
19
My husband got a particularly nasty zit on his upper lip when he was 17. Every time he shaved, he shaved the surface off, and it bled like a mad bastard. So he stopped shaving his upper lip. I knew him in middle school without his mustache, but by the time we met back up in high school, he had it. He’s 44 now, and he’d just look weird without it. However, his hair is very, very dark brown, almost black, as is his 'stache. He is starting to get some silver in there, though.
His mustache is not one of the things that attracted me when we started dating, but it never repulsed me, either.
Every year at hunting season, I stop shaving for a week while I hunt the wiley whitetail. Then shave it off before I go back to work. I’m 32 now.
This last year, I left the goatee on for an extra day, and went to work. I knew it looked completely rediculous on me. What floored me was that my co-workers were embarrassed and no one said a word. 
I shaved it off the next day, and my coworkers looked visibly relieved.