That happens sometimes with Navetsea's skins. They are very close to real life skins, so they might look blotchy. I use hairy4 for my main characters, as I think the faces are so natural looking, and navetsea adult hot as default. Then I use kursoberina's skins for my darker skinned and Asian sims, mangosmoothie for my oriental (Egyptian) sims. Those skins are beautiful, and less "blotchy", but also, in my opinion, not detailed enough.
Comparison navetsea and mangosmoothie:
https://greywitches.files.wordpress.com/2018/11/tgw01-29-119.jpg
Here's a link to a page on my blog where you can see a lot of the torso. The skin looks a little blotchy from the back, especially the spinal column...