I dislike when the cover artwork for an LP is changed. Sometimes this is done for reasons of cost, or perhaps because the original artwork was considered too risqué.
A good example is the cover of Soft Machine's debut album. The original was a gatefold sleeve with cut out windows through which a circular insert could be rotated like a piece of clockwork. The second 'modification' was the censorship of the naked model sporting a large key in her back - she is a 'soft machine', shown on the inside of the gatefold as well as on the rear. You only see her from the behind, but to satisfy prudish American sensibilities, a black bikini was crudely printed on her for the American market. :doh:
An example of a "censored" sleeve:
