1) The SNP are seen as toxic to many of the electorate in the rUK
2) The rise of the SNP lead, in part, to the demise of the Labour party in the 2015 election. Not just by taking seats of Labour in Scotland but because there was a debate over a Lab-SNP coalition, which the Tories used to frighten people to vote Tory.
I don't see you disagreeing with (1) maybe the cause of toxicity but the cause is a secondary issue.
Do you actually think I think that or is it some form of SNP spin that you want to associate me with someone in the LibDem party.
I think that is entirely right, and I think it is perhaps a touch tricky to see this if you are embedded in Scotland rather than rUK.
The mistrust of the SNP isn't inherently their political positioning on the left-right spectrum. Indeed there are plenty in England who are largely aligned in that respect, and lets face it they aren't much different in traditional political terms from Labour. No, the mistrust is that the SNP, don't and don't even pretend to represent the whole of the UK. So their motivation is suspect. I'm sure you can see that.
So in rUK following the referendum the fact that Labour campaigned against the SNP is either largely an irrelevance because rUK people can't vote SNP so don't really care whether they are campaigned against or not, or a mild positive - standing up for the whole of the UK in opposition to a clearly partisan block.
So in rUK the negative effect for Labour wasn't that they'd campaigned against the SNP in the indyref, no it was the fear factor that a hung parliament might lead to the 'clearly partisan' SNP holding a balance of power and only being interested in Scottish self interest which as you might imagine didn't go down well in London, or Manchester, or rural Oxfordshire, or Cardiff or Anglesea.