Most of the eggs have movement inside, so those are easy.  But these others, I just don't know either.  I was able to move one of the questionables to the definately developing side tonight.  I saw a little chicky swimming in there!  My RIR eggs are the easiest to see into by far, and they seem to be developing more quickly than some of my others.  I'm turning into a candling junky, and unfortunately, there just aren't that many pictures out there, especially of eggs that are more pourous, or splotchy looking.  I've seen the candling progression pics here on BYC, but haven't really come across anything else.
Edit: Okay, I feel like someone should put a little hat on my head that says "duh!"  I was reading around here and came across someone who said they candle from the top... I've been holding the eggs upright and sort of candling from the side or bottom.  Well, after reading that, I went back and candled the 8 that were questionable.  4 have swimmers in there.  The others are still questionable.  I can see veining, which leads me to believe there is a swimmer in there, just hiding under the air cell.  Definately encouraging.  And, I was able to clearly see the air cells, and they all look really good. Some are bigger than others, but are intact.