As everywhere else in the UK, Scotland is and old place with an long-standing culture full of subtle (as well as not so subtle) complications and fault lines.
Certain sensitivities are common to all parts of the UK, but others are quite specific to Scotland, or even its particular parts or regions.
I am not attempting to write an anthropological guide here, just point out certain aspects of the culture that a traveller or a visitor might want to be aware of, either to avoid an unpleasant moment or just to enhance the understanding of the place.
Nationality. Never, ever call a Scott ''English'' and never refer to Scotland as ''England''. Although it is understood that people from outside the UK will use ''England'' as a metonymy for the whole of Great Britain, and often for the whole of the United Kingdom, it's a very bad form to do it in Scotland. The Union of both countries is still an extremely controversial thing, and in fact the Edinburgh government is (at the time of writing in 2012) in the hands of SNP, a nationalist party whose main (and some say, the only honestly held and real) objective is to achieve full independence for Scotland. The history of Scottish-English wars is long and illustrious and the memory of some battles, particularly the massacre at Culloden (although that was fought actually, along dynastic and religious fault-lines more than national ones) is still alive. Just. Remember. Scots. Are. Not. A. Subset. Of. The. English.
The attitudes to the UK project are more complex and although majority of the Scots support some form of independence, many do not. Historically, many Scots played an important part in the imperial expansion of the UK, and Scottish thinkers, writers and philosophers are an integral part of the mainstream UK intellectual life.
Religion. Overall, more of a fault line in Scotland than in England but less than in Ireland. If you talk to people from Glasgow, you are likely to hear about ''sectarianism'' which will inevitably refer to the tribal rivalry between the Protestants (specifically Church of Scotland) and Catholics, and will be often connected to the conflict between the supporters of the city's two main football clubs, Rangers (the Prod one) and Celtic (the Catholic one). Historically, many a big social upheaval in Scotland had a religious element, including both of the Jacobite rebellions of the 18th century. Nowadays outside Glasgow the Catholic-Protestant differences are significantly less pronounced, in line with the increasingly secular character of the culture in all of the UK.
In the Highlands, and particularly in the Western Isles, the Wee Frees, an extreme protestant church that split off the main Scottish Kirk, still has a powerful influence in many areas, where hanging out washing on a Sunday is frowned upon, playgrounds are chained closed and ferries don't run on a Sabbath.
Region. The rivalry between Edinburgh and Glasgow is legendary, each of those fascinating cities quite particular about its respective image Edinburgh's is one of a refined, cultured and decidedly upper-middle class snobbishness with an undercurrent of decadent darkness dating maybe as far as it medieval days. Glasgow considers itself a down-to-earth, working-class, genuine, friendly and non-snobby, with an undercurrent of violence and a gangland mythology to rival that of London's East End (not for nothing a head-butt is known as a Glasgow Kiss).
There are minor reflections of that archetypal fault-line, for example the antipathy between Perth (a snobby market town that considers itself a refined city) and Dundee (''Scumdee'' in the words of many a less refined Perth inhabitant).
The Highlanders (aka ''tchuchters'', although this word can also be applied to any person from the countryside even if not from the Highlands) are often regarded with reciprocal suspicion by the people from the Central Belt, while in the Highlands themselves the inhabitants of the East Coast are considered dour and repressed by those from the West, supposedly possessed of more of a free spirit and Celtic ''craik''.