They are great for taking your sweat away from your body. The problem is they also get you skin oils as well, which is why the smell a lot more than cotton for example that only holds onto the water part of your sweat
Personally, I love merino wool t-shirts. Try one out, a summer one that is thin
It is surely less accurate than it was presented to be a decade ago. I have searched for info I knew it was online 10 years ago, and most of it is either lost entirely, or Google is useless nowadays and can’t find it anymore