As ESG-related investments strongly increase their importance, so do ESG evaluation metrics that can prevent greenwashing practices. This article provides an overview of the main ESG Evaluation metric provided by S&P Global Ratings, later describing why such evaluation method should be taken into consideration in Private Equity funds and their investment strategies. It will then evaluate whether ESG really makes a positive difference on society by diving deep into an excursus on greenwashing, so to better understand the phenomenon and to explain how a lack of measurement can affect investment performance. Both topics of ESG and greenwashing are becoming increasingly relevant nowadays as they are closely linked to wider country-level sustainability goals and investment returns targets for Private Equity firms.