[en] The lack of scaling of flux pinning forces found in some superconductors is discussed. As examples, data from three systems of superconductors is analysed: (1) Nb₃Ge and pseudobinaries based on Nb₃Ge made by chemical-vapour deposition; (2) sputtered Chevrel-phase films of PbMo₆S₈; and (3) sputtered Chevrel-phase films of Cusub(x)Mo₆S₈ (1.6 <=x<= 2.5). The lack of scaling in all three systems is explained by assuming sample inhomogeneity. Moreover, it is found that modified scaling laws are quantitatively obeyed if redefined pinning forces or redefined magnetic fields are used. The redefining procedure depends on the nature of the inhomogeneity particular to each of the three systems investigated. (author)