  We present a systematic investigation of the low-frequency charge carrier
dynamics in different charge states of the organic conductors
$\theta$-(BEDT-TTF)$_2$$M$Zn(SCN)$_4$ with $M$=Rb,Tl, which result from
quenching or relaxing the charge degrees of freedom on a geometrically
frustrated triangular lattice. Due to strong electronic correlations these
materials exhibit a charge-ordering transition, which can be kinetically
avoided by rapid cooling resulting in a so-called charge-glass state without
long-range order. The combination of fluctuation spectroscopy and a heat pulse
method allows us to study and compare the resistance fluctuations in the
low-resistive quenched and the high-resistive charge-ordered state, revealing
striking differences in the respective noise magnitudes. For both compounds, we
find strongly enhanced resistance fluctuations right at the metal-insulator
transition and a broad noise maximum in the slowly cooled charge-crystal state
with partly dominating two-level processes revealing characteristic activation
energies.
