I love my headlight washers!
When I was doing my pre-purchase inspection, I tested the washers and like others have said, foam shot about 20' in the air, completely soaking my car and the Range Rover beside me. The plastic plug on the driver's side shot out with it to boot.
After all that, I was able to get two hundred bucks off the price as I said I'd have to buy an OEM replacement part to have it fixed!
They can be valuable indeed!