Interesting problems !

What constitute interesting problems ? Interest is relative and hence we cannot generalize interesting problems isnt it. For someone working with large data sets, interesting problem would be faster execution with multiple processors/machines. For someone working on a thick client interesting problem, could be related to UI transitions, etc. For someone working in a garbage disposal industry, interesting problem would be how to recycle efficiently.

I would say, people generally test others with problems they consider interesting to themselves, which might not be globally interesting or challenging enough.