Well, first of all, guilty in here, I use them for trekking but also in a normal day.
But I got to be honest with you: sometimes they do, sometimes they don’t. The problem with the so called High Tec shirt’s it’s not the fabric, but for example, the way that the shirt it’s made.
Some of them are only t-shirts as the usual ones, made with fiber so they can be fresh and could evaporate fast your sweat and dry. This one’s could be very good for small trekking’s for one day or something like that (or to use in a normal day, going to work, as I use them). The problem is that they tend to get wet with your backpack.
Then you have other type of t-shirts with some sort of net under your arm pit and back, wish I think that are the best High Tec shirts, because these are very fresh and they don’t tend to get wet on your back.
They are “making” some of them for trekker’s, but if you find them very expensive, check the Cycling area, usually the material it’s the same, and it works in the same conditions. It was what I’ve done, and I spared almost 50% of the value.
P.S: I don’t know why, probably it’s the fiber, but with the first ones I tend to have my nipples sored sometimes :?
Diogo