A pumice stone works wonders on callouses and dead/dry skin.. however they cause tiny scratches to normal skin which after sometime, turn dark and patchy.
Some people have used a pumice stone to dislodge ingrown hair from their arms and legs and did perm damage (scarring).
Loofah/body scrub is a safer option.. as they're less abrasive.
I've never heard of the dettol remedy.. should try it out the next time I get a tan :(