This is very mixed. It depends on what you want your apparent age to do for you.
18 and looking 21 and older would be an advantage when trying to procure alcohol. 50 and looking 30-ish would be an advantage because you still retain your apparent social maturity, but you aren't necessarily past your 'prime'.
21 and looking 30 would be a disadvantage because you run the risk of looking like the creeper who tries to pick up younger women. Plus, women in the 18-30 range still have plenty of young-looking hairy guys to choose from and, in my experience, the majority of them still don't have their priorities arranged such that a man's lack of hair isn't an issue to some extent.