Something that drives me up the wall as a Rogue is when my team is on the ropes and our mages spells are nearly out I step up and use one of the rogues best assests to save the day - Use Magic Device.

I pull out that Ray of Ice scroll or Wand of Missles and activate it only for it to tell me that I can't use it. Despite NOT having a red backdrop to it the entire time I carry it around in my inventory (seen when you drag the cursor over the item)

Now granted I probably didn't have enough UMD skill points to use that item yet, but it'd be really nice to have that red background on the item BEFOREHAND so that I know I can't use it yet.

This would be greatly appreciated.

For crafted wands and scrolls, it's a roll -- sometimes you can use, sometimes not, depending on the roll. Sometimes you may not have enough UMD at all to make the roll, most scrolls are probably in that situation.

Items you find (including some wands) run off a separate script, so the red/not red thing applies -- no roll involved.