Quote Originally Posted by Ivojedi View Post
Before using and equipping? not really. If you put it in a socket and equip it, valid ones will add to the skill from your skill tree. Invalid ones will add a second line in your skill mods list.
So, unless I loot one myself, I have to assume any available to me are very likely non-working. Would it be hard in future when replacing non-working attachments with working ones to add some indicator (text color, font size, all caps, or description altered in some other way) to make it possible to tell?