If the criticism is made that the Labour party aren't listening to people, and the answer is "but the SNP..." (or, equally, "but the Tories...") then it is the wrong answer. Indeed, not only is it the wrong answer, but it actually proves the point - the person doing the criticising wasn't talking about the SNP or the Tories, they were talking about the Labour party.
The thing is, there are two categories of 'criticism'. There is indeed a category of criticism that is simply unthinking, contemptuous sneering. This generally comes from your implacable enemies, who would find something to object to, regardless of what you do or say. Labour gets this criticism from the likes of the Daily Mail. And the correct response to it is simply to ignore it.
But then there is the valid criticism from people who want to like you, who want to support you, and, in the case of Labour, who want to vote for you. There are an awful lot of people in that category in Scotland. And when those people start deserting the party in droves (as they are), and when they state their main issue as being that the party doesn't listen, then that's a problem - and it's one that the party absolutely should recognise and take action on.
Because the alternative is that the people who want to be your supporters will very quickly become soured on what you're saying, and move very quickly to the other camp. And then you've lost them, permanently.
(That said, the big problem that Labour have is that in fact they are listening. But they're listening to the swing voters in Middle England, since they're the ones who generally win elections for one party of the other. Problem is that their needs are significantly different, and often opposed, to those of traditional Labour voters in Scotland, in the North of England, and in Wales. And by chasing one group of voters, then, Labour open themselves to attack from the SNP, Plaid Cymru, the Greens, and even, scarily, UKIP. In which case, maybe they're done.)