Just deviating a little from Steffen's and Andrew's points:
I grew up in an area only minutes from wineries in South Aus. In my twenties I stalked the wineries of SA and Victoria. I found in the 70's Victorian wines were not up to the quality of SA.
The same I noted for Qld wines. I rarely found a good one.
In the 80's Victoria excelled. So did Qld in the late 90's.
Now it has become difficult to judge which are better. The quality of QLD wines has improved to the point where I buy them regularly. Rather than just sampling.
My point is: The difference gap between good and poor wines has been closing and a bad wine today is an average quality from yesterday.
This has been brought about by the improvements in all parts of the industry.
50 years ago, judging wines was much easier. Not so today. That is reflected in certain wineries in Western Aus.
A few wineries produce wines using age old traditional Italian methods. (No not grape stomping)
These are absolutely disgusting. Highly oxidized, cures sunburn, makes weak men strong and strong women weak. Best drank with clenched teeth to prevent the ingestion of seeds.
Once you sample any of these you will realize just how far wine making has come. It is no longer comparing Model T Fords to present day Fords. These days it is Porsche and Ferrari. The packaging is different but they perform with similar results.
The same applies to wine. Even the $4 and $6 wines are now drinkable. From $15 upward there are some excellent wines.
Cheers