If there was a power that went something like "Minor action. Effect: Make an intimidate check.", would you let the user intimidate unbloodied enemies into surrendering?
Gloaming cut doesn't say anything about circumventing the normal stealth rules. It just lets you make a check at an additional time.
If a power said "make an intimidate check" you could make an intimidate check against every foe, and only non-bloodied foes would be effected. You are allowed to target non-bloodied foes with intimidate, but they suffer no effect on a hit.
But this is just a technicality, I understand what you are trying to say. What if intimidate could only target bloodied foes, and a power said "make an intimidate check against each adjacent foe". Would you be able to make the check against un-bloodied fores? The answer is yes. If a power (specific) tells you that you can use a skill against all adjacent foes, then you use the skill against those foes without having to meet the normal requirements for using the skill.
If a power says "you score a critical hit" or "you gain combat advantage for this attack" you gain those bonuses even if you do not meet the prerequisites for those effects. The power does not need to state 'even if you didn't roll a 20, even if you do not have flanking, etc'.
Gloaming strike states that you make a stealth check, therefore you make a stealth check. The power need not list a statement for each requirement of stealth that you do not meet. You make your stealth check and proceed to the portion of the 'becoming hidden' rules that describe the effects of success or failure.
Note that the rules for stealth also state that you cannot become hidden as part of the same action that caused you to become revealed. Attacking causes you to become revealed, so by your argument gloaming strike would never be able to grant a stealth check, because it does not specifically state "you may become hidden even if this action caused you to become revealed".
You might argue further that it is 'obvious' that the power is intended to allow you to make a check as part of the same action that caused you to become revealed, but that it is not obvious that the check is intended to work without cover or concealment. This argument doesn't hold any water if you are going by RAW. Powers under RAW function according to how they were written, not how they were intended to work. Note that sometimes Wizards CustServ makes a ruling that is different than RAW, so we will see how that works out.
Edit: There are clearly some errors on Wizard's part in the wording of these powers. If you read the "shadowy rogue" description, it suggests that you should take attack powers that grant movement to benefit from the cunning sneak class feature. This suggests that Wizard's intended for cunning sneak to be used when hiding with powers such as gloaming strike, which in turn implies that Wizard's intended for other characters to require total concealment and superior cover when using these powers. Note that this is contradictory because:
1: Cunning sneak only works with move actions, therefore it has no effect on the powers that Wizard's suggests using it with.
2: Gloaming strike does not require any cover or concealment to make the stealth check as I have argued in this thread, which has been confirmed by their CustServ
http://community.wizards.com/go/thr...stomer_Service_Answers&post_num=591#391307925
I hope to see some errata and clarification soon