What do these lyrics mean to you?

I mean this, I'm not sure if you could say the same. Week after week after week Idolatry is wasted reverence, idolatry is the yellow on your teeth. Gasp for the truth you once lived.

maybe that you are living a lie and believing in something fake and horrible...
and that is the yellow on your teeth

Well I think that it's like;

The person is being blunt and truthful to someone about how they think that they're blinded and throwing away their life by being awe-stuck over someone who is inadequate and inconsequential to their life.
How the person they are idolizing shouldn't be in that position since that person is equivalent to a yellow-ish stain on their tooth. Is so insignificant and unwanted, and it's tainting their image and how they're viewed.
How this person thinks that this someone should push their idol away, and go back to the way they were before they got lost in an obsession over something so revolting and destroying to them...

And yeah thats what I got basically... lol

These lyrics are from The Devil Wears Prada song Ben Has A Kid

I believe that the lyrics, as with the rest of the song, is a call out to those who once had faith in Christ but have since either lost their way or renounced the faith they had. I believe its calling out for the Christian world to honestly face what they have become and how the idols of secular society have taken over even the strongest of convictions. Its saying that the idolatry being shown is a waste in the long run. That each person's yellow stain (sex, drug, alcoholism, themselves, etc.) isn't hidden but ever displayed by an ever false smile and that they are missing the big picture of something that is much larger and more eternal than themselves. I believe its calling for those who have gone awry to drop the facade of the idol ruled life they live and rejoin that bigger picture.

Great song choice by the way.