I find that my whole back and hip is asymmetrical for cracking.
They used to be fairly even, twisting one way and then the other would produce a string of clicks down each side of my back, sometimes as far as my sacrum and hips. Now my right side always cracks very easily (normally in the hip or lumbar area) whilst I can almost never crack my left side.
I think I may have caused some laxity in the joints of the right lower back and hip - when I try to twist left it feels like I don't have enough leverage to crack the left side joints. Sometimes when I twist left, the right side joint will crack!
This worries me a little and I've been trying to stop cracking these joints, however it's currently so easy to crack my right lower back and hip that just twisting towards someone or turning over in bed can cause the joints to crack!