Smooth hydrophobic polymer treatments on inorganic surfaces were prepared. Their macroscopic properties (static contact angle and advancing and receding contact angles) were evaluated, and each surface structure was finely characterized using AFM measurements. Our work dwells on the difficulties of characterizing hydrophobic surfaces: it must be done not only in terms of work of adhesion but also in terms of blocking energy. A now mechanical protocol is used to directly measure this blocking energy of water droplets between smooth hydrophobic surfaces, and the results obtained using this simple model are in close agreement with theoretical energies. This measure allows us to distinguish two surfaces that otherwise should be considered as having the same properties considering their work of adhesion.