Hi,
I recently went on a trip and forgotten that the passport had also taken a swim. Had no problem going through Hong Kong, Macau, Beijing and return. Interestingly, the only person who mentioned it were the airline personnel - the counter person and the GA for O8 mentioned I should think about getting a replacement.
Having said that, I'm contemplating getting a new one as well since the picture is harder to see now.
Wooe