Whether or not Ukip manage to secure one of Scotland's six European parliamentary seats, their current standing in the polls, at about 10%, is a remarkable improvement on their showing only three years ago, when they obtained less than 1% of the vote in the Holyrood elections.
Nigel Farage, by returning to Edinburgh to campaign after his rough reception last year, hopes to convince Scots that a successful result is within his party's grasp. But his claim it would also prove a game-changer for the independence referendum is a much more dubious proposition.
Even if Ukip do manage to secure support in Scotland as well as the gains they are widely expected to make in the European elections, it is unlikely to indicate Scots have discovered a sudden enthusiasm for independence from the EU, and will tell us even less about how they may vote in the referendum. Even amongst Ukip supporters, the EU is not the main policy priority.
But then, the inconsistencies of Ukip's policies make it difficult to pin down any common factor behind their support other than dissatisfaction with the established UK parties. While presenting themselves as a free market party, they advocate tariff barriers and protectionism, and a range of populist domestic policies involving government regulation that no-one on the left would dare propose. Even on their most contentious but probably most popular stance, immigration, their stated policies would actually increase immigration.
If inconsistency were enough to damn a political party, however, Ukip would hardly be alone in facing protests. The level of support the party has attracted (even if that is much more pronounced south of the Border) entitles them, at the very least, to a hearing. It may not be hard to find failings with a party whose own leader described its last manifesto as "drivel", despite having written the foreword to it; or to identify particular candidates and campaigners with ludicrous or downright offensive views.
But if Ukip do seem especially prone to attracting supporters who look like, in the Prime Minister's words, "fruitcakes, loonies and closet racists", that is not the party's stated policy and it has - perhaps belatedly - taken to expelling and disciplining members who express offensive views. With that in mind, it is ridiculous that Mr Farage's visits to Scotland should be greeted by the kind of vicious hostility and intolerance that actually hands him the moral high ground.
Ukip's policies on immigration, and its views on the kind of society it would like the UK to be, may be hopelessly muddled, and many may find them authoritarian, illiberal or objectionable. It is perfectly reasonable to protest. But to pretend Ukip's programme is akin to fascism, while attempting to deny them a platform with tactics themselves reminiscent of the most intolerant political movements, is absurd.
If Scotland really has no time for Mr Farage and his party, that will be made clear enough in a couple of weeks' time. For the time being, however, the best way to rebut Ukip's arguments is by argument.