Paul Clarke drops some serious science on the San Francisco Chronicle in an exhaustive takeout about vermouth -- the history, notable brands (with tasting notes!), styles, and even recipes. Well worth your time.
Here's a wonderful sentence:
[From] the approach taken by most American bartenders - who typically dispense vermouth with atomizers, eyedroppers or simply a delicate hand when mixing martinis - vermouth could be considered some sort of bibulous antimatter.
And that's an accurate observation, too; last week at Landmarc, I ordered a Hendrick's Martini to go with my steak salad. "And don't be shy with the vermouth," I requested. Our waiter was surprised and said he'd be sure to note that, and mentioned that their Martinis didn't have vermouth unless the customer requested. I emphasized that I did most certainly request it, and that a Martini without vermouth is just cold gin (or worse, vodka. Why drink an ice-cold glass of something that's alcoholic but legally flavorless?) The waiter got it, and shortly delivered a pretty good Martini. (I'd previously gotten some fine Manhattans at the bar there, so I knew that they knew what they were doing, even if their customers are gun-shy with the vermouth.)
But yeah, this blanket fear that vermouth is made up of equal parts fortified wine and plutonium has got to go -- it's just a flavor, and a good one at that. (And as Clarke makes sure to emphasize, store your vermouth in the fridge, and it does turn once opened -- that's probably a large part of why some people hate the stuff.) Viva vermouth!