While social democrats allowed ultra right party Vox to enter the parlament (first time since franco), it is not so bad: the leading right wing party PP probably will not ally with Vox since they both would not have majority. A nice feature of Spanish politics is that they have a party with a percentage of communists (led by Yolanda Diaz), something what would be not possible with ultraconservative countries like Poland.
Absolutely, it's basically what Parenti describes in Blackshirts and Reds where he talks about ABC leftists. We need solid class based analysis which is ultimately what MLs do.