I got a call from a HR person today doing a background reference check on a great individual. This individual used to work at one of our clients, but opted to move on, and now is in the last stages of signing on with a different firm for another online marketing position. The individual provided my name as a reference as we've known one another in the industry for several years.
The HR person asked me this question, which I'd never heard and thought was great:
If you were to put the candidate on a two-person team, what strengths would you want the other team member to have to best complement the candidate?
Asking about what would complement someone best -- what a super-nice and effective way to get at someone's less strong areas.
Putting it in that positive way -- rather than the conventional "Can you describe the candidate's weaknesses?" -- got me to think and to speak more more freely.
Polite. Smart. Effective.