Well, color me incredulous

I've been watching a lot of TV lately.
In my defense, I'm unemployed, and at least, oh, 10% of what I watch is educational. Fault me if you want for considering "Showbiz Tonight" educational, but it IS on the Headline News channel, and I've learned a number of things from watching. But I digress.
More TV means more commercials, of course, and even though I mute the television I usually end up watching them. As I've watched them, something has been bothering me, and since it's bothering me, I'm going to make for darned sure that it bothers the rest of you as well.

I've seen a number of television commercials for haircolor - L'Oreal is the one that comes to mind. They'll show a celebrity - Heather Locklear, for instance, or Andie MacDowell, sitting at home with Excellence Creme on their heads, lounging around while their color processes, talking about what a great product it is, blah blah blah. What I want to know is, are we honestly expected to believe that these women color their own hair at home? Heather Locklear for one strikes me as the sort who pays a couple hundred clams for a simple haircut. I don't think she's going to spend eight bucks at Wal-Mart on haircolor and do it herself in the bathroom at home. I just don't buy it.
I've been to beauty school. I know entirely more about the chemistry of haircolor than I ever wanted to. I'll spare you the details, but suffice it to say that there is a difference between the color you buy in a box at Wal-Mart and the color that licenced professionals use at hair salons. They're made of different chemicals and they work on the hair shaft differently. If a person uses box hair color month after month, it builds up. The hair isn't going to look completely pretty. Salon color doesn't do quite the same thing. That's not just something that hairdressers say to get more money out of you, it's basic chemistry.
I don't mention this to wow the general populace with my knowledge of color chemistry. I mention this because if Andie MacDowell was really coloring her own hair with Excellence Creme every month, it would look more greasy than lustrous and the color would be one-dimensional and uneven. Either she's got a head of hair unique among humans, or somebody's lying.
Guess which one I'm going with?