I'll just say at 40 there are situations where I dye my hair.
I'm at the "salt and pepper" stage, and it doesn't look bad but certainly if you show up in a high pressure situation people will have a better impression of you.
Since I go heads down for months at a time and only get a haircut when I'm going on tour for some reason, it's pretty cost effective.
If this is really an issue of phone interviews if you contact me I can do a 10 minute mock interview and try to diagnose any communications you have that could be offputting to people.
I probably have a few years until I have to start dying it for anything, but I guess I could see where that would make sense eventually. Thanks the ideas - I think with the suggestions here that it might be enough to get me started on trying to redefine these interviews in the future.