If you watched ESA a few episodes ago, they fished the Amatikulu estuary and they caught bartail flathead after bartail flatheads using only drop shots. They were using a Berkley prawn with a jig head and used a retrieve wherby the prawn was bounced on the bottom of the estuary. And off course they were very successful.
I fished the same location recently using drop shots as well. Used Berkley sandworms and Berley shrimps on a one eighth jig head. I also used the same retrieve. And off course I caught absolutely nothing!!! However on another occassion a mate of my while fishing the white water gulleys @ Sheffield beach managed to hook and land 1 small rockcod and 1 blacktail.
I am cartain that drop shotting works, however the conditions need to be right and you need to match the choice of lure and type of retrieve to suit the present conditions.