Gorpcore
Outdoor gear as streetwear? Fashion? Does it really matter?
First, clothing worn while hiking should be functional. Full stop. If it doesn't keep you warm, cool, dry, itch-free, UV protected or any other practical application, ask yourself why.
Second, materials. Is the material right for activity, designed for the beating it'll take on the trail.
Third, construction. Just as picking the right materials, how it's made is important. Extra stitching in areas that are prone to tear. Double up material in other areas. Just well made overall. Usually holding it will tell you a lot about the piece.
After these are considered, you could think about how it looks off trail or on. Could you come back into town and go straight to a restaurant? Do the clothes still smell ok. Materials matter.
If outdoor clothing is marketed as fashion first, think twice.