Artists get better with age. Programming is an art. All tedious tasks get automated away. All that's left are design decisions. Making good design decisions is what people mean by "taste". Taste gets better with experience.
A young person may have more physical energy, but to paraphrase Steve Jobs, they don't have any taste. Their surplus physical energy could be a liability, as they'll just write more code that's hard to maintain. Of course there are exceptions. Don't discriminate by age in either direction. Ask for experience, and make your final judgment after examining their portfolio (just as you would an architect or photographer), looking for signs of good taste.
Further reading: "Taste for Makers", by Paul Graham, http://www.paulgraham.com/taste.html