A friend killed his motherboard whilst attempting to install some RAM. I couldn't see any damage to the RAM slots so I assumed it was from ESD. It was along time ago though I can't even remember the system. Think it was an AMD 3200+ system or something. I've always touched a non painted part of the case with the PSU plugged in and switched off and never had any issues.
I used to be anal about ESD until I accidentally touched the pins on a video card GPU while running (this was back in the day when GPUs were in QFP packages instead of BGA.) The system kept on chugging like nothing happened, even though a couple of 1" sparks jumped to leads on the GPU. I still have that video card in a drawer and it still works today.
I abhor ESD bands and refuse to wear them because they usually have one metal button on the most sensitive underside of your wrist. In the winter months back when I was in high school tech lab, you'd get shocked constantly, enough to where most of the guys ripped them off and threw them across the room in a fit of rage from the pain. You might argue "why don't you just rotate it?" - well you can't because the cord is right next to the button and will just whip back to the underside of your wrist. And UGH, does anyone remember those shitty desk/chair combos which had the metal rivets in the base of the seat? You couldn't move without getting your leg or ass shocked.
My RAM horde is stored in plastic bins, motherboards are stored on boxes with foam board and hard drives are in stacks. Never had an issue in 25 years.
As for what I use to clean my computer parts, I use these (specifically the green bottle or the harder to find unscented as citrus gives me a migraine):
I prefer these over alcohol wipes or alcohol in general because they don't dry out within a minute of pulling them out of the bottle. I usually get at least a dozen uses out of every single wipe before tossing it for being dirty. They leave basically no residue and have the added benefit of sanitizing nasty computer parts and leaving them smelling better.