We here report on the influence of heteronuclear dipolar decoupling on the 27Al 3QMAS, 5QMAS, and the double-quantum filter–satellite-transition magic-angle spinning (DQF-STMAS) spectra of a strongly dipolar-coupled system, gibbsite. The requirements for heteronuclear dipolar decoupling increase with the order of coherence evolving in the indirect dimension of a two-dimensional (2D) experiment. The isotropic line width of the high-resolution 2D spectra, in samples like gibbsite, is composed of four parts: the distribution of isotropic shifts (δISO, δQIS), the homogeneous broadening related to the proton–proton flip-flop terms, the 27Al27Al homonulcear dipolar couplings, and the 1H27Al heteronuclear dipolar couplings. It is shown that, even in the case of gibbsite, where a strong proton–proton bath exists, the main resolution limiting factor in these experiments resides in the 1H27Al dipolar interaction.