The thing that makes this statement so ironic is that advertisers are the ones that determine what to show the American public, and to a great extent that defines what the "wholesome all-American image" is.
In other words, what they are actually saying is that she doesn't fit their idea of the "wholesome all-American image," so they aren't going to incorporate her into it.
Before we go too far down this road, let me explain the role market research plays in terms of what gets on the air and what doesn't.
Let's say a network is considering whether or not to put a show on the air. What they do is look over the script, and figure out who the likely audience for that show will be. Once they produce the pilot, they pull together a focus group made up of people from that likely audience, and some people who are not from that likely audience. If the target members in the focus group like the pilot, that's good. If the show has any appeal at all to those outside the target even better. If nobody likes it, it doesn't air. During the follow up that is usually done after testing the pilot, members in the focus group typically get to talk about the details of the show: "character A was too mush of a dickhead," "character B wasn't funny." Then the network assess the feedback it got, makes changes to the pilot, and the whole things starts all over again. At some point, a go/no-go decision is made. Then of course, once the show is on the air, then the Nielsen ratings guide the choices made by the network/producers.
So the marketers do not create, or define anything. All they do is measure. The people who say what America likes/doesn't like are the regular, everyday folks in the focus groups, and the regular everyday people who contribute to the Nielsen ratings. And in case you're not aware, Nielsen is very good at making sure that their families represent a cross section of America. Literally EVERY group is represented. Why? So they can measure accurately, and report back to the networks and the marketing pros exactly who is watching what.
You notice it didn't interfere with Kristi Yamaguchi winning the 2008 Dancing with the Stars competition.
That's a good point. Maybe she was not the "wholesome all-American" for some advertiser back whenever, but she certainly didn't have that problem with DWTS audience. They loved her.