It's a risky occupation. Some people die of infectious diseases and undertaking would take special training.
Overall, you would be providing a special service. On a facebook group I belong to, someone had extended special thanks to a barber we all knew who had given his deceased dad a haircut so his dad would look more like his old self at the wake.
Whether in the basement or the attic wouldn't really matter. I think I'd be fine with it. But I'm very happy to be retired and would like to remain as such.