Temperature dependence of the polarized reflectance spectra have been measured on the single crystals of theta-ET2MM' (SCN)(4) [MM' = RbCo, RbZn, CsZn] salts. The reflectance spectra of RbCo and RbZn salts exhibit drastic change around 190 K for samples cooled down slowly (dT/dt similar to -0.1 K/min). This spectral change disappears for the samples cooled down rapidly (dT/dt similar to -1 K/min). The reflectance spectra of MM = CsZn salt exhibit Drude-like future down to 20 K. Charge-ordering patterns on these salts are deduced by the spectral analysis using mean-field calculations.