First of all, it does not have to be vertical. You could drop shot from the bank.
Second, it does not have to be deep either.
As far as where... wherever the fish are. If they are on the brush, by all means throw it in there. It may get hung up from time to time but that's just part of fishing.
If they are in the open, do it there too.
Crappy Piles. Sometimes theres one or two bass below them. If you have a graph, you should be able to tell the difference. Only one way to find out usually
Dropshot is a kickass technique. Try it and enjoy. Only one way to find out.