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.