Adsorption excess isotherms of binary liquid mixtures have been calculated from synthetic adsorption energy distribution functions characterizing energetic heterogeneity at the liquid/solid interface. In order to see consequences for the adsorption isotherms, the distribution functions were varied systematically. In this way, the sensitivity or the lack of sensitivity of liquid-phase adsorption isotherms over the whole concentration range for changes in energy distribution functions became evident. The question of to what extent it makes sense to use liquid adsorption measurements to obtain relevant information on a solid's energetic heterogeneity is answered.