If you don't use a vacuum though the dust just flies out and settles in your house. I usually hold the vacuum near where I think the dust will fly out without touching any components. Never had an ESD problem yet.

> If you don't use a vacuum though the dust just flies out and settles in your house.

Do it outside.

Could just dust it outside. Though if you're not personally running into any issues I suppose it doesn't matter. Probably depends on the vacuum and the weatherd

Is a shop compressor with an air gun adequate or is that air too moist or oily?

Compressors can get a build up of condensation in the tank. I've personally never had that be an issue, but it's definitely a concern.

A bit of moisture actually helps to reduce the chance of static discharge, shop compressed air is probably one of the better ways of doing this. I've done it for many years like that and never had a computer fail on me due to cleaning.

The best thing is to avoid doing this on cold winter days when static build-up is very rapid, and to avoid touching the guts of the computer with your fingertips near the circuitry until you have grounded the case against your fingers. Easy enough with metal frames, much harder with plastic ones.