Using the Red Channel for the high-end fashion look basically whitens the skin. It is fully explained in Frank Dorhof's excellent book Mastering the Model Shoot, pages 250-251. Frank is an amazing photographer from Holland.
Here is a sample retouched image of model Tiffany Felisha:
The technique is very simple. Start with a merged layer of the retouched image, add a new blank layer and name it Red Channel. Click on the merged layer to activate it, open the Channels Panel, click on the Red Channel, do a Command-A (Control-A) to select it, Command-C (Control-C) to copy it, click on the blank Red Channel to activate it, then Command-V (Control-V) to paste the black and white Red Channel into it. Set the layer blending mode of this layer to Soft Light and adjust the layer opacity to your liking. Here is the technique applied to the above image, with the layer opacity set at 50%:
Here are before and after studio images of Tiffany. The layer opacity of the Red Channel layer was also set to 50%:
This interesting technique can be copied into a Photoshop action, so that all you have to do is fine tune the layer opacity.