I have never liked vermouth. At all. I avoid cocktails when it is an ingredient. I have Dolin but maybe the issue is I'm not refrigerating? I was not aware.
Vermouth is a wine, and just like all wine, it will oxidize and go bad. If your bottle is over six months old, replace it. Old vermouth is the cause of most bad cocktails, but rarely gets the blame it should.
This is great info. I never really thought that much about vermouth. I bartended in college and we never refrigerated it, or replaced it for that matter, but that was a long time ago and craft cocktails have certainly upped their game.