I have a 7 month old who is using Bum Genius brand cloth diapers. He has ALWAYS wet through all his clothing at least once per day since starting with me. Mom started bringing the ones with the double liners to help but it was still happening. I was going crazy having to wash everything so often that I almost considered telling mom I would no long be willing to allow the cloth diapers unless she brough plastic pants to cover the diapers.
Mom did alittle reasearch and came back and told me that what was happening was that when the diapers were being washed/soaked they weren't being "stripped" properly so they had build up left on them of laundry soap and even urine that wasn't completely washed out so when the baby urinated, the urine was basically just beading off as if the diapers were water proof rather than absorbing anything.
Bottom line is after mom changed how she washed and stripped the diapers, it hasn't happened any more so maybe you should ask the mom how she launders them as from what I have read, it does require specific techniques or processes to get them clean.