Correct. Deionised water is a perfect insulator, IIRC (20Mohms/10mm).

It's safe to say the washing machine was hooked up to a tap water supply.
Even leaving out the detergent, this isn't a good insulator and as mentioned is full of minerals etc. which will leave residue.

If you were to try to remove water from a device with alcohol what would be the best way to go about it? I am imagining stripping it all down and using Q tips.