Kinda like violin spiders...... you just don’t want to fiddle around with them.
I saw one once. Deceptive. Their webs are large and irregular. Worst of all, the initial bite doesn't hurt that much but then the bite blisters and creates a nasty ulcer.
I find a couple of black window nests in our garage every three weeks or so in the summer. I feel bad but I kill them. They nest in walkways and corners where people might brush against their nests. I don't want the family getting bitten.
I tore the large garage door frame apart once when I found one hiding behind the frame. Not good if the little guy fell onto someone as the door opened.
The tell tale sign of a black-widow — lots of dead hard-shelled insects near their webs. They are one of the few spiders that have large and strong enough fangs to penetrate the shells of the insects.