The halo effect has…. pernicious consequences. In one study, the same examination scripts were rewritten twice, once in good handwriting and once in bad handwriting. They were then given to two sets of examiners: each saw all the scripts with half written badly and half well. They were all told to disregard the handwriting and to mark purely on the content. On average the scripts in good handwriting received considerably higher marks than those in poor writing……

If a person has one salient (available) good trait, his other characteristics are likely to be judged by others as better than they really are. Handsome men and women tend to be rated highly on intelligence, athletic prowess, sense of humour and so on. In fact physical appearance has little to do with such other characteristics: there is a small correlation between being handsome and being intelligent but it is not enough to account for the mistakes people make in their judgements.

Sutherland, Stuart. Irrationality: the enemy within (pp 20-1). Pinter & Martin. Kindle Edition.