A good counter to this problem for the interviewer is to pick something that is extra-domain to your problem space. A previous employer I worked with used "Desi

A good counter to this problem for the interviewer is to pick something that is extra-domain to your problem space. A previous employer I worked with used "Design the object model of a Chicken" as a starting point. The interviewers would then act as a potential client and we'd go back and forth with the candidate over their approach. Definitely rough on candidates, but it does give a reasonable window into their thought processes and who the interact with other people.