There are cases when a small change, such as capture of a simple particle, has a significant impact on the molecular properties. This indeed happens with the "proton sponges". We show how the substituent effect (SE) and the presence of an intramolecular hydrogen bond (IHB) modulate the properties of 1,8-bis(dimethylamino)naphthalene, its protonated form and their 4-X substituted derivatives. The following substituents have been chosen: X= H, NO, NO2, CN, CHO, Cl, F, CH3, OCH3, OH and NH2, placed in the para position relative to the N(CH3)2 group. The HOMA index was applied to study changes in the aromaticity of the naphthalene moiety. The strength of the IHB was estimated by Espinosa-Molins-Lecomte equation. QTAIM and IRI were employed to investigate differences in electronic structure and non-covalent interactions caused by substitution. Finally, SESE and cSAR were computed to evaluate the SE characteristics. NBO analysis was carried out to evaluate the SE influence on the lone pair of nitrogen atoms. We have shown that the presence of a strong intramolecular HB significantly weakens the substituent effect. For electron-donating substituents, the SE was found to have a greater influence than hydrogen bonding in the DMANH+ series. The opposite result was obtained for electron-withdrawing substituents.