The reason that 'mistakes' are made in the last round is because we unconciously have strong associations for certain words for each of the categories.  Even if on a concious level we think we don't. It simply illustrates that.

I don't especially agree with the wording of the results as 'you have shown a strong preference for x,y,z' - I think 'shown a strong association of' is a better way of phrasing it. Some tests say association, some say preference - and you don't have to answer any of the questions in order to take the test and get a result.

I expect that it does change across cultures and countries and for me it changes across categories too.  I still think it is interesting as an indicator of where associatons/prejudices lie.