You are bringing up age as criteria for hiring someone.
Besides, it's against the law.
If you were looking for someone to share your bed with, I think taking gender and age into consideration will be OK.
Not so much age. There are bad habits that you see at different stages in EFL careers. You get fresh graduates with no experience who think they can teach with no technique or preparation just because they are magically foreign. Then there are teachers with 5-10 years experience who are stubborn and don't listen to management. Then teachers with 10+ years experience who are too tired to put in a good performance because they have taught the same lesson 100 times. I have seen, and been, most of those types. So with every level of experience there are red flag personality traits to watch out for. These flaws are all nearly impossible to catch in an interview, as well.
On the other hand you get excellent teachers at all ages.
Here's an interview question: Complete this sentence: David Icke is a...