I have to say, my experience of the English hating Scot, isn't really one of blanket hatred, but rather one of hatred for a 'certain type' of English person, or should that be English attitude?. This was never more clearly defined than in the 1980's, when a Government used the country as a social experimenting ground, and simultaneously abandoned huge tracts of traditional regional policy support, with all the inequalities and injustices that went with it. The distribution between the haves and have nots which already existed, was duly exascerbated with ever greater polarisation. The Scots weren't the only victims of course, and most are well aware that other areas suffered too. Its natural enough however, that when you can see hardship and suffering, and can attach a demonstrable 'cause and effect' explanation as to why this is happening, that you will then develop a hostility to those who you perceive to be responsible for it, those you perceive to be sustaining it, and ultimately those who you perceive to be seemingly re-joicing in it. I don't blame the Scots in a lot of respects.
It wasn't always so though. The Scots had a deep Conservative tradition, and I'm pretty certain they were the majority party in the 1950's North of the border. So it's not necessarily and engrained political hatred. Instead its the result of a series of frequently pernicious, and decidely deliberate actions.