That is close to the method I use. Wait for a really dark and humid night without a moon. Head out to the country away from all lights. Leave the motor running and wait for yours eyes to adjust to the dark. If the plug wires are bad you will see flashes of light here and there. If they are really, really bad the entire wire may glow from one end to the other.scarredpelt said:In the dark, with a spray bottle of water. Really show up the pretty lights.