I don't think the problem with Good Charlotte is the make up. Its just another excuse for people to bag them.
Punk is a culture about anarchy - breaking the rules, doing what others don't want you to do. Punk rock is supposed to follow a similar tune. It has simple rhythms, played at nutcase speed, and generally makes some sort of heavily sarcastic political observation.
Take Green Day for example. They sort of went off the track a bit, veering more into generic rock for a while, but with American Idiot they've returned full circle. I can't think of an album that more encapsulates living in a world of paranoia and fear... of post September 11 USA.
Good Charlotte don't follow this punk trend. They dress up in fashion-punk get up, get whored around by the record label and produce music with little true observation or insight. They're pop stars. They're no more punk than Avril Lavigne.
That said, I don't necessarily mind GC. Or Avril for that matter. I have the Young and the Hopeless Album. But it doesn't sit with the other punk albums in my CD collection - with the Clash, the Ramones, Green Day, NOFX and the rest of it. It sits in the pop section.