  We investigate both thermoelectric and thermodynamic properties of the misfit
cobalt oxide [Bi$_{1.7}$Co$_{0.3}$Ca$_{2}$O$_{4}$]$^{RS}_{0.6}$CoO$_{2}$. A
large negative magnetothermopower is found to scale with both magnetic field
and temperature revealing a significant spin entropy contribution to
thermoelectric properties giving rise to a constant S$_0\approx$ 60 $\mu$V
K$^{-1}$ equal to the high temperature asymptotic value of the spin 1/2
entropy. Low temperature specific heat measurements allow us to determine an
enhanced electronic part with $\gamma\approx$ 50 mJ (mol K$^{2}$)$^{-1}$
attesting of strong correlations. Thereby, a critical comparison between
[Bi$_{1.7}$Co$_{0.3}$Ca$_{2}$O$_{4}$]$^{RS}_{0.6}$CoO$_{2}$, other cobaltites
as well as other materials reveals a universal behavior of the thermopower low
temperature slope as a function of $\gamma$ testifying thus a purely electronic
origin. This potentially generic scaling behavior suggests here that the high
room temperature value of the thermopower in misfit cobalt oxides results from
the addition of a spin entropy contribution to an enlarged electronic one.
