I remember selling black salt when I still had my online Wicca & New Age shop.
I've never used it myself and still wouldn't. First of all, my house is clean. I also live alone so ifever there's something it's related to me.
I put a spiritual lock on the house (after I'd cleansed it) when I'd first moved in. Took me a few hours, but worth it to make me feel safe :) I came from a house where a helluva lot was wrong and off. So a safe haven was important to me!
I sometimes cleanse with white sage, for instance if I've had a lot of stress. And if I feel it's necessary I re-affirm the spiritual lock, mostly only downstairs then.
I've picked up something at some point and then cleansed my aura -outdoors- with... white sage.
I don't feel salt or black salt is particularly strong, but that's me. Maybe it depends what you want to use it for.