Question about the glow wire test

Hello!

I had some starting problems with my Passat 1Z, so I held a test lamp to the spark plugs -> I couldn't even see the test lamp flicker. Is it possible that they can fail so completely that nothing moves electronically? If my old Passat 32b had defective spark plugs, at least the test lamp still worked a little (I've only been driving a TDI for two weeks: I didn't think that these engines still depended on the spark plugs). Thanks in advance!!!!!!!

Regards, Christian

Hi

Why shouldn't a light bulb be able to burn completely, but also partially?

Incidentally, a light bulb test is only meaningful if you use a main headlight bulb.
Due to their high power consumption, even minor defects in the bulbs ("1/4 burned out") ) is noticeable due to the tired flickering, while a normal test lamp still shines brightly.