I think cats have a bit more cognitive ablilty than people credit for. Ive seen enough evidence to be fairly convinced (both with my own cats and other peoples cats) that they will react to cirtian things in cirtian ways and in a sense hold a "grudge" against the offending party. Even Remus, the most loving and personable cat I've met (maybe Im biased lol) will shun people who have treated him badly. Yeah its an avoidence response but it does take at least a little cognative ablity to form the association to begin with.

Boy Im long winded today lol