Another stain question, is this a micro fiber thing?

[Biscuits & Gravy]

My BGs and Thirsties come out of the wash all clean, but the MF inserts have stains and still look dirty. They are used in the BG pockets, so they are not even the first line of contact with the poop. I wash every other day. Am I doing something wrong? I'm using Purex right now, and was using 1/3 of the man. recommended amt., but have started using 1/2 since the inserts don't seem clean. I do a cold rinse before my wash.

[Michigan Mama]

I do think it's an mf thing. I feel they tend to hold onto "stuff", and that's also why some people have stink issues with them. Ours aren't too bad. Sun helps, but I also do an extra hot rinse after my hot wash cycle.