I think that Earl has it worked out. The reason I think that the Sex Pistols could make "I did it my way" work, as well as their other stuff, is that they had a vision or a social message and their music was the vehicle for that. The Sinatra song was pure farce, which is different to Pogue-a-likes parroting a style that they don't seem to understand at all.

The Pogues have a vision of how their music can be, and why they are doing it. There will always be poor imitators who can't understand why they don't get rich & famous on what they see as exactly the same "formula".

Helen