The practice of deciding which category to submit your contest score in after the contest is over, and after information on (claimed) scores of potential competitors is public. The purpose of category shopping is to attempt to win a plaque or other recognition in a category that was less competitive than the category that was actually selected in advance. This could be done, say, by claiming SOA when no assistance was used, or even by claiming multi-operator when only one operator was present. This practice is unethical and contrary to the spirit of competition.
An Amateur Radio Blog by DX Engineering 
