Can I make a suggestion here which may help?
If you see a picture and you like it, that's great - we all love praise.
However, if you feel the picture could be improved, but the author has NOT asked for a critique, keep it to yourself. Don't post anything. It may well upset the author. He has not asked for opinions on the photo - so please don't prejudge.
If the thread is C&C, then the author has, by posting there, asked for some feedback.
One last thing - there's a difference between critique and criticism. Be polite and positive.
Alan