We show that the broad X‑ray photoelectron lines of silicon oxide on silicon arise from a continuous statistical distribution of core-level binding energies. Statistical simulations spanning compositions from Si to SiO${}_2$ reproduce the full extent of this broadening, reaching $\sim 5$ eV for SiO${}_{1.0}$, in quantitative agreement with 0.23 nm layer-resolved spectra reconstructed from Ar${}^{+}$ sputtering data. This continuous distribution blurs distinct spectral fingerprints of local structural motifs, thereby challenging conventional chemical state assignment in oxide X-ray photoelectron spectra.