If smell & taste perception vary by person & can each day with the same person, what is the real value of anothers tasting notes?That's a good question, particularly for people like me who are happy to pick out "fruit" when others are describing which Spanish province the tangerines in the marmalade came from.
As Tom Vanek points out, though, not only is another person's tasting notes no guarantee of what I would taste, it's not even a guarantee of what the person who wrote the notes would taste again. So if there is any real value in tasting notes, it's not the value of an objective description of smell and taste.
Let me run in the opposite direction, then, and propose that the value in tasting notes lies in that very fact. If we only value objective descriptions of smell and taste, then one set of notes is all we need, and we can get them from the distiller as easily as from any other source.
What tasting notes are, though, are a record of a personal, subjective, not-altogether-repeatable experience of drinking a glass or two of whiskey. For me, the word that adds value in that sentence is "personal."
Tasting notes are part of a conversation about drinking whiskey. The meaning of, "This is what I smelled and tasted," is not, "This is what you will smell and taste." That wouldn't be a conversation, that would be a lecture.
Rather, the notes are an invitation to reply, "Really? This is what I smelled and tasted." Whether we smell and taste the same thing, or different things, the comparison of our individual, personal, subjective, not-altogether-repeatable experiences gives us more to talk about -- and, quite possibly, an idea or two of what whiskey to compare experiences with next.
And that, for me, has value.