Malcolm

I have blue hair. Haven't had an interview yet but my hair is blue in the pictures I sent in. I hope it's ok! It shouldn't matter but we never know... 

Your interview has nothing to do with your wife's hair color
your relationship and living conditions and marriage do
you,  yourself ,  could walk in with multi colored hair 
your fingerprints need to match 
 
not the hair
don't overthink the process just get the necessary documents together

'Unprofessional'?  Why would one need to look professional outside of the context of a job interview?

Hi there! 

I've got my Green Card interview in a couple of weeks time and my wife recently dyed her hair, and she brought up the fact afterward if the Immigration Officer might think that it would be unprofessional to have. I was thinking about it and I think its just got on my nerves however we do look young and I do not want to give off the stereotype of being unprepared or seeming naive. 

Cheers

Just bring original of supporting evidences, if they need to keep anything, they will make copies of them. Good luck.