The question and answer format enables the author to fill a lot of space without providing much information. It is also very repetitive. The advice is really just common sense. It can be summarised as: casual does not mean dirty or scruffy; take your style cues from senior management; what is acceptable in one company will be frowned on elswhere; dress for the job you want; it is always better to be too smart.
A useful manual for anyone who is in any sector of business. A definative explanation of what dressing 'casual' actually means. From who to observe-to common mistakes people make by wearing the wrong clothing in the work place.