I found that the longer my dry vermouth is open (stored in the fridge), the more vermouth I want in my Martini. After maybe 2-3 months, I really enjoy stirred vermouth.
It's definitely true that dry vermouth loses a lot of its aroma after a couple of weeks unsealed in the fridge, but at least with the vermouths I know (Noilly Prat and Dolin), the taste of fresh dry vermouth is too much on its own. Kinda circles back to the "most people don't actually like the taste of vermouth" thing that led to ultra-dry Dry Martinis, but somehow in a different way - 2-3 months of fridge is pretty different from years at room temperature.
I'm prepared to accept that my tastes are just weird, though.
Funny I also have a Dolin and a Noilly Prat in my fridge, sitting open for months/years. When the bottle is new, I sometimes have a bit of vermouth on ice, but not when it’s older. Recently I’ve been sneaking in amaro instead of the vermouth. I do like the taste of vermouth, especially the ones they serve (on the rocks) in restaurants in Barcelona. But I agree that the lighter the taste the better for mixing.
save