Just wanted to chime in as I purchased a Pad A Cheek Mask Liner for my mask, the Dreamwear Full Face Mask, last week to hopefully help with two issues: red marks from the mask that were starting to appear on my chin and mouth, and maybe to absorb some moisture from either humidity or drooling that was waking me up or making it uncomfortable and hard to fall asleep or stay asleep.
First of all, Karen and her team (I exchanged emails with someone named Kristen) are amazing. They were fast and responsive to emails when their site was down, and they mailed my mask the day after I purchased it. Their website is pretty top notch too - easy to navigate, and you can set up an account on the website to track your purchases. I did this after I made my purchase as a guest, and it automatically found my order and linked it to my account which was really cool.
As for the mask liner itself, which you can get in either blue or grey, I received it on Saturday, so I've only used it two nights. That said, the look and feel and quality of the cutting and stitching of the velcro and shape of the liner is great and worth the money as far as I'm concerned, especially since the only other option seems to be disposable liners that all have terrible reviews on Amazon (at least for the ones for my mask).
As for how it works, again I'm only two nights in, but so far it seems to have solved both my problems. The redness is gone or almost gone, and the mask either wicks away moisture or actually helps keep my mouth closed cause I haven't drooled much if at all the last couple nights. The microfiber feels really nice on my face, and I find I'm fidgeting with my mask less to get it into place. If there is any fidgeting, it's me making sure the nose holes on the liner and mask are aligned, which they pretty much are - I think I might like to fidget with things too much. My mouth and nose are still getting moisture from the humid air, but not so much that my lips and chin are wet from humidity.
I might post an update in a few weeks just to see if things are still great or if any issues have arisen, but so far, this mask liner is a Godsend.
That's pretty resourceful. See my signature for a similar approach. 
