Barbie has her sticky legs, and the Monster High dolls have what I am calling "Leaky Head Syndrome." this problem is also intermittent, so you never know which dolls will be leaking, or how severe it will be.
below I have two box liners for dolls that I purchased at the same time (from Amazon, of course). on the left side is Mad Science Lagoona. you can see that what ever substance is leaking out of her head has caused some discoloration to the cardboard liner she is attached to. on the right side I have an arrow pointing to the spot where Physical Deaducation Ghoulia's head was attached- no discoloration.
the substance has an oily or waxy feel. while I have not noticed it causing discoloration to the dolls' hair, it does noticeably affect the texture, feel, and styleability of the hair. I have noticed some of my dolls that did not have leakage on their box liners have started leaking when I stored them lying down.
I don't know what this substance is. I've heard that it is the glue that is used to hold the dolls' hair in. now I wonder at what point the ghouls will start going bald. if the glue is leaking out now, it can't be doing a very good job holding the hair in, can it?