When I read this by Hungarian academic Tamas Dezso Ziegler, I could not help thinking he had a point. The point, as I understand it, is that by calling people like Trump or Farage populist, when at the same time we call Syriza or Podemos populist, we are in danger of diminishing or normalising the danger the former pose. He suggests this wide definition of populism
“could be useful because there is not necessarily a moral evaluation behind it: if they would use far right demagoguery, or fascist politics, it would show something dangerous, extreme. It would ring the bell to us all. Populism does not do so.”
“an anti-establishment orientation, a claim to speak for the people against the elites, opposition to liberal economics and globalisation, and often (but not always) a penchant for authoritarian governance.”
It seems to me that a quite different conceptualisation of populism is expressed by Jan-Werner Müller. You can tell a populist by whether they claim to represent ‘the people’, which is certainly not all the people, but instead just the ‘real people’. The others, be they immigrants or the 48%, just do not count, or worse still are ‘saboteurs’ trying to thwart the ‘will of the people’. And, critically in my view, populists are prepared to overturn the institutions of democracy if they believe they are frustrating what they perceive as the will of the people. The populist, if you accept Müller’s account, denies pluralism. They are naturally authoritarian, and so are happy to tear down the elements of a pluralist democracy. 
Thinking in terms of left or right tends to get in the way here. The more appropriate axis to thinking about this definition of populism is social liberalism and conservatism. A social liberal, almost by definition, is not going to attack democratic pluralism. Once we recognise that, we can see why parties of the right that use socially conservative policies to attract votes are particularly vulnerable to morphing into (or being taken over by) populists in the Müller sense. Indeed this is a point he himself makes, as I quote here.
It seems to me that Brexit can illustrate both types of populism. The definition of populism based on anti-globalisation might describe quite well the average Leave voter. The Leave voter tends to be against immigration, and as a result be prepared to roll back globalisation, and this often goes with a belief that the elite or establishment no longer listens to them. In contrast some of the prominent Brexiters, and certainly the newspapers that swung the referendum vote, are populists in Müller’s sense. They are quite happy to talk about the will of the people, and take away power from judges and parliament to ensure the will of the people as they see it prevails.
This is why I have considerable sympathy with the Hungarian academic who I quoted at the start of this post. Populists in the anti-globalisation sense may be a problem, depending on your view of globalisation and liberal economics, but they are not really dangerous for democracy. Populists of the kind Müller describes are, as our history tells us.
In the US, we are not just talking about Trump, but most of the Republican party: a party that appears to go to any length to preserve its gerrymandering of voting districts. In Hungary and Poland we have seen many attacks on pluralistic democracy justified by nationalism and racism. Both, like Russia or the far right in the US, are happy to scapegoat someone who happens to be a wealthy Jew as an enemy of the people for the crime of standing up for liberalism. That certain UK newspapers find common cause with these authoritarian regimes and the far right in the US by scapegoating the same wealthy Jew on their front pages should be a wake-up call that these newspapers are no longer part of a pluralist democracy but have become instead its enemy.
 Tear down rather than reform. Of course when reform becomes destroy has to be judged, but in most cases that is not very difficult.