You all must fly some very well kept aircraft.
Fly in a typical club trainer or microlight with polarised lenses, and any cracks or stresses in the perspex screen turn into a rainbow. Very pretty, and certainly good fun, but not really helping a good lookout.
In terms of radios, I've only ever had problems with two, one was in a C42 microlight, the other was a bendix king DME. Strange it only seemed to be that unit since I've never had problems with others.