Capitalism in Decay

[Classical] Fascism was interesting for a few reasons, some of them being its relationship to the labour movement:

• ᴉuᴉlossnW was a prominent socialist until their expulsion from the PSI for their nationalist views, and if we take them at their word in their last testament while captured by communists, they considered themself a socialist
• Fascism managed to bring other former Marxist communists into their ranks, notably Nicola Bombacci, a founding member of the Communist Party of Italy in 1921 until their expulsion for fascist views in 1927
• Fascism was economically a class-collaborationist ideology (specifically corporativism, from the Latin corpus, body)

Now, of course, we have the benefit of hindsight and can see what a disaster Italian fascism and its friends were and the name of 'fascism' is forever tainted. But theoretically a modern equivalent could similarly appeal to both nationalists and the socialist-leaning today in a similar way. Fascism doesn't logically imply racism, nor does it necessarily exclude certain types of progressivism: see BUF gaining large support from women by being pro-suffrage, see environmentalism of eco-fascists, and consider some modern neofash parties adopting social democrat policy points.

With all this in mind, what were the early warning signs that Fascism was not going to be pro-worker, despite its rhetoric? How well do you believe socialists will be able to spot them?