Major Brands in Media: Has Alcohol Quality Gotten Better, Worse, or Is it all Advertising?

I’ve noticed that in a lot of period pieces, high society types are depicted drinking alcohol from major, classic brands that are considered mid to low shelf these days. In media, brands like Cutty Sark and Smirnoff are enjoyed on the rocks by high powered executives. These days, you’d be more likely to see a homeless alcoholic drinking a plastic bottle of one of those brands, and people of means would gladly pay an upcharge to avoid that stuff.

So, for anyone who knows: are these depictions of drinking in the past accurate, or is it all just product placement? If they are accurate, what explains the drastic change in drinking these days?

Were Cutty Sark and Smirnoff actually good at one point in history, but declined in quality as their businesses over-extended? Or were those just the best options around at the time, and liquor quality has improved drastically in better, higher-shelf products?