The bad loss list is established for C, H, N, O, Al, Si, P, S, F, Cl, Br, and I containing compounds. For example, CH radical has a mass of 13 Da, but is not normally found as a loss in mass spectra. CH 3 radical, with a mass of 15, on the other hand is frequently observed. As another example, no combination of elements has a mass of 10 Da that has a chemically meaningful structure with normal valences. BeH radical has a mass of 10 Da, but we are assuming that you aren't working with Be.
Poor losses are generally of low probability.
However, poor losses can't be rejected on chemical grounds. For example, a loss of 82 from the molecular ion is unlikely. However, H 81 Br has a mass of 82 Da. Robert A. W. Johnstone, Malcolm E. Rose, Mass spectrometry for chemists and biochemists, 2nd. Ed. , Cambridge University Press, Cambridge, Great Britain, 1996.