Artifacts have long been reported in the scattering of helium atoms from surfaces, particularly in the time-of-flight spectra used to study lattice dynamics. They are caused by elastic scattering of atoms in the low-intensity tails of the incident helium beam wave-vector distribution, which simulate inelastic scattering events. These ``deceptons'' have only been observed near the Bragg diffraction peaks. In this paper, modulation of the coherent elastic helium-atom signal, due to interference effects caused by surface scattering from multiple terraces and possibly other surface defects, is shown to give rise to additional artifacts in helium-atom time-of-flight spectra. Experiments on rutile ${\mathrm{TiO}}_{2}(110)$ illustrating the occurrence of these modulated deceptons (or m deceptons) in time-of-flight spectra of the specular reflected beam are reported and discussed. Additional discussion is presented to show that these modulations can also influence the intensities of the previously described deceptons around the Bragg diffraction peaks.