Homeotropic nematic layers of MBBA, oriented by self-assembled layers (on glass substrates) of dilauroyl phosphatidyl choline (DLPC), cetyl trimethyl-amonium bromide (CTAB) and silane orienting agent (ODS-E), were studied by phase-sensitive flexoelectric spectroscopy method. DLPC solutions in chloroform provided multilayers with different thickness on dipped glass substrates, depending on bulk DLPC concentration. CTAB solutions in water provided, on the other hand, just monolayers, with surface density depending on pulling speed of substrates. Finally, ODS-E solutions provided orienting layers that can be cross-linked at elevated temperatures. The viscoelastic spectra of these layers contained information about surface dissipation of orientational energy under variable structure of orienting layers that may, or may not, dissolve partially in the nematic.