I can confirm that I have seen similar pictures during development of u8glib. While i also think that some of these results would make nice looking pictures, they are usually not intended.
The ST7920 controller is probably the device which consumed most of my attension during u8glib development and support. Here are my suggestions (from endless discussions with other users):
- Use the latest u8glib version. Nearly all recent updates of u8glib include fixes for the ST7920
- Solder your wires.
- Use short wires (less than 10cm)
Which serial interface did you test? HW SPI or SW SPI?
Oliver