Yes vinegar, salt and Dawn dish soap mixed together does work to kill weeds for some reason.
I've tried it myself and it works just as good or even better than commercially made weed killers.
The vinegar, salt and dawn dish soap are all natural and won't cause anyone or pets any harm when used as a natural weed killer.
I use the mixture of vinegar, salt and dawn dish soap in a sprayer and spray the weeds and within a day or so the weeds start dying off.
Spraying the area with the natural weed killer also helps any future weeds from growing.