Sometimes I notice, doesn't bother me unless it's really overgrown. I actually saw a lady out in town today who had regrowth that went down to her ears, it was all black and the bottom of the hair was white blonde. It was quite horendous.
The only time I ever think "ooh they need to go to the salon" is when I see blondes with super dark roots. It's ugly. I used to highlight evey once in a while but stopped b/c I could never get back to the salon enough and I was one of those with the ugly roots. I just stay natural now.
I always notice but it doesn't really bother me. After all, I've gone a few weeks without touching up before (not when I was blond though),
I remember when Kelly Ripa was still on All My Children and she let her dark roots grow out for months and months. She got so much hate mail when really, the reason she didn't dye her hair was because she was pregnant! Since they didn't show her from the boobs down unless she was wearing something baggy or had something blocking the view of her belly, no one knew!