Dear Miss Snark,
Recently you remarked that if a prospective author informed you he/she was "ancient" that would not be a plus in your book. It raises the question of how much weight you give the author, as separate from the manuscript. Suppose you received a novel that you loved, and then discovered the author was "ancient". Would it give you pause? Would you think twice if the author, was garrulous, anti-social, clingy? (You pick your turn-off.)
Most authors, I'd guess, think it's the manuscript and only the manuscript. Maybe there's other stuff, aside from the givens of civility and a modicum of professionalism, going on.
Miss Snark is nothing if not avaricious. She likes the idea of signing authors who will generate exquisite works of great value (and cold hard cash) for years to come. That said, sometimes she's forced to sign people over the age of seven and hope for the best on the actuarial tables at Monte Carlo.
Age isn't a disqualifier any more than it's a qualifier. You can be 107 and write YA books. You can be 10 and write true crime. I don't care. I look at the writing.
However, once we get to "am I the right agent for you" then it's not the writing. It's all about you and your "needy, garrulous, anti-socialist, clingy" self. Some of those make you a very very bad choice for SnarkCity. Others make you a charter member. When I talk to clients before signing, one of the things I'm trying to do is get a sense of that.
I certainly wouldn't say no to a great novel cause the author was 103 but I also wouldn't sign them to a three book deal.