Cerys Matthews denies The Voice, where she appears as a mentor, is all about singing ability.
The x-Catatonia frontwoman helps Sir Tom Jones in the Battle Round stage of the series as he whittles down his acts for the live shows.
Cerys, who duetted with Sir Tom on the Christmas hit Baby, It's Cold Outside, told The Sun: "I don't think you can completely say it is not about image.
"That is untrue. Of course it is primarily about the talent but then image has to come into it. It does matter. You have to connect with people and to put a show on. It's about everything."
The Saturday night BBC One show featured the coaches with their backs turned to the singers in blind auditions so that they could judge on the basis of what they heard alone.
But Cerys said: "The most important thing is someone who is unique, with raw talent, who can tell a story. You want to be able to touch people and look the best you can."
The Welsh star said it was "emotional" choosing which acts to take through to the live shows.
"These people are there because they care. You are treading on their dreams," she said.