How would the Imperial Player use the scouted card? (Imperial Assault: Jabba's Realm)
It lets the Imperial player re-roll a defense die. As a cost/balance for this benefit (in addition to the exhaust), if a Dodge is rolled, the player can't keep it. (It is changed into a weaker, but still okay, evade.)

So it let's you have a re-roll, but a little weaker one than usual—if it's a white die. If it's a black die the Imperial defensive player is re-rolling, this additional cost wouldn't come into play. (Just the exhaust cost in this second case.)

I think the confusion might be coming in if you think you have a choice on whether or not to apply the Dodge to Evade after the re-roll, which is incorrect. If you re-roll, you must apply the conversion to the result (when applicable).