If you are debugging VTK on Windows with Visual Studio, there are some natvis files to configure your debugger available to as part of DebugTools. They configure the debugger to show a synthesized, easier to debug with, version of some of the basic data structures used by VTK.
For example: VTK stores all its point data in a contiguous array. Efficient, but difficult to debug the point ids for polygon 52 if you don’t already know to start looking at point index 200. Debugging becomes much quicker if the contiguous array can also be shown as an array of cells each having an array of points, where it becomes trivial to examine which point ids are used for a given cell.