Hello, just wondering how one cleans the old aroma of coffee past from plastic parts, like a thermos? I got one of those contigo cups and usually drink coffee from it, today filled it with tea and blergh... I tried hitting it with Dawn and a toothbrush to really get into the threads/nook/crannies but it's still there, a google search says a baking powder/vinegar soak works.... any other ideas?