Things that come to mind for bad schematic review:

* Linear voltage regulator with high input voltage powering an obviously very power hungry load.

* No ESD protection/current limiting for sensitive pins exposed to outside world.

* Tantalum capacitors with very narrow voltage rating margin

Another tactic I like (something similar is mentioned in sibling comment): a small design problem representative of real life task.

For generic EE position I like the following: "Suppose there is a project using this microcontroller. Project requires this micro to power an externally connected solenoid with this specification."

I find this reveals a lot of the seniority/thought process of the candidate: what (if any) questions candidate is asking to better understand the problem ("Do I need to consider output short circuit? What are the cost/size constraints? Don't we need a internal/external feedback?"), what is their process of component selection (if that is required in job description) and the suitability of this process for the needs of particular company.

Now, if only I could come up with similar strategies for software positions...