Let's say that Lazarus the Lazy is an eighth level wizard. He is too lazy to wash his dishes, so he simply uses them once and throws them out every day. Each night before bed, he summons an Unseen Servant. "Make me a spoon!" he commands. (Wisdom was his dump stat.)
The Unseen Servant "can't perform any task that requires a skill check with a DC higher than 10 or that requires a check using a skill that can't be used untrained." But Craft is usable untrained, and "wooden spoon" is listed as an example of a DC 5 check, so this should be within its capabilities.
What should the roll be? Can the servant take 10?
For bonus credit, can this answer be extended to other skills the servant can use?