Would it be bad to attach a trailer to a fully carbon bike for an extensive tour? I'm probably going to be buying a fully carbon bike in the near future... and was wondering if it would be a good idea to use a trailer for it. I had the look of panniers, and I know I would be more comfortable with a trailer...

The thing to remember with carbon is not to clamp it. What kind of trailer do you have and how does it attach to the bike? As long as it doesn't involve hose clamps or anything similar, you should be ok. Very few carbon frames have braze-ons for racks anyway, so the trailer may be your only option.

When you say you "know youd be more comfortable with a trailer" how do you know? Personal experience, or a thought experiment?

Most people use steel touring bikes and panniers for a reason, but that said, you can use a carbon racing bike and trailer if you want to. the gearing will be wrong, the position will likely be uncomfortable for the long haul, and trailers are quite heavy. not to mention the plastic bike probably wont hold up to a very long trip...

for a one off tour of a few hundred miles, it would work, for multiple tours or a long trip (1-2-3k miles), you might want to give up any pretense of looking cool, and just get the best equipment for the job.

my 2c anyway.

You could look at a trailer that attaches via the rear wheel's quick release mechanism, as opposed to the style that clamps to the rear stay.