I'll give you even one more, water is a very poor conductor and you could run your computer submerged in it. The thing with water is that it's an universal solvent. It's these impurities (e.g. salt) that dissolve easily in water, add ions and make it conductive enough to make that a bad idea. Honestly just look up water. It's weird as hell.
Industrial setting. PCBs were sometimes gross as hell. Had a dishwasher at work just for PCBs. Lowest setting and they came out looking factory new (Not sure I'd use a dishwasher I put my cutlery in though, depending on how your dishwasher works you might recycle that tasty flux-containing PCB water all over your nice plates next wash). Mildly soaped water can work wonders on flux, too (but dishwasher soap can be kinda corrosive) and there are even special soaps. Mainly just need to be mindful of places that could trap water, like the modulators in C64s in the post linked above me, not even in them but also below them. Think capillary action. Ideally you remove such parts first. I washed many a retro system like this privately, too. When you're done you can also spray the wet parts with IPA, they'll dry quicker. (IPA = miscible, lower boiling point, higher vapor pressure. Just don't smoke while spraying)
With the smoked CPU I wonder... you know how easy it would be for a company like intel to "grassroot" something like this? Even if it's debunked later, the damage is done. Just thinking out loud and not saying that happened here.