What makes an image worthy of being in a portfolio

Unless every person who sees it goes WOW, without needing to elaborate, it should not go into your portfolio.
Unless it is consistent with the primary body of work for which you want to get hired, it should not go into your portfolio.
Unless it is technically executed at a professional level of mastery, it should not go into your portfolio unless a deliberately rough style is something that you have been doing and exhibiting deliberately and consistently.