In this mini-review, we consider the specificity of collective excitations in disordered media, mainly in liquids. We discuss the difference between proper excitations in disordered media and plane harmonic waves and the related problem of effective excitation damping. A detailed comparative analysis of the spectra of collective excitations in ordinary liquids and superfluid helium is carried out. Such aspects as the phonon and roton parts of the spectrum, the phenomenon of "fast sound", shear waves and ?"mixing" of longitudinal and transverse excitations in liquids are considered. It is shown that excitations in liquids determine their thermodynamic properties both in the normal and superfluid states. Despite the qualitative similarity of the spectra of superfluid helium and ordinary liquids, there are significant differences that, in our opinion, have not yet received an adequate theoretical description. We emphasize the large differences between superfluid helium and superfluid Bose condensates of ensembles of ultracold atoms. An assumption is made about the possible major role of the high zero-point energy of helium atoms at ultra-low temperatures both for understanding the features of excitation spectra and for the phenomenon of superfluidity itself.