I'm fairly certain that age does play a factor, at least with Google. I don't as a rule, optimize my sites at all. I don't do link strategy. I don't even submit them. SEO is a special request thing I charge extra for, and I don't pretend to be an expert. If you're looking for hardcore optimization you need an expert. I tell my clients to dig down deep and cough up at least 6G a year to do the job right.

Still, some of my older sites are starting to appear for no discernable reason at all. If people are linking to them I don't know about it, and they don't come up on a link check.