Bug in extrude? ( Possibly just a display bug ).

 From:  Crusoe the Painter (CRUSOE)
How about for a curve, when you select "Show points" if it detects stacked up points, display their handles in red? If you show the stacked points, thats good enough.
And if it's too expensive to run all the time, a "Check for stacked points" command would be useful to have.