You can say no and still help with a solution.
Instead, what was happening was that after they asked their question and I answered, "no," they'd walk away and not attempt to get my help again with it afterwards.
For the longest time, I thought they were like me and that they were looking to have their question answered. They weren't. They were trying (clumsily) to get help with their problem.
Depends. Are we assuming you can't draw in seven dimensional Hilbert space?