I have a Nyquil stain on my passport that has been there for about 5 years. I've been to at least 60 countries with this passport and no one has ever had a problem with it. I also had pages added in LA without a problem. Today I took it to the US Consulate in Shanghai to get more pages added and they refused, saying it was damaged. Grrrr. Next I try the Consulate in Paris. I expect they won't have a problem.