  The semiclassical description of two-dimensional ($2d$) metals based on the
quasiparticle picture suggests that there is a universal threshold of the
resistivity: the resistivity of a $2d$ metal is bounded by the so called
Mott-Ioffe-Regal (MIR) limit, which is at the order of $h/e^2$. If a system
remains metallic while its resistivity is beyond the MIR limit, it is referred
to as a "bad metal", which challenges our theoretical understanding as the very
notion of quasiparticles is invalidated. The description of the system becomes
even more challenging when there is also strong correlation between the
electrons. Partly motivated by the recent experiment on transition metal
dichalcogenides moir\'{e} heterostructure, we seek for understanding of
strongly correlated bad metals whose resistivity far exceeds the MIR limit. For
some strongly correlated bad metals, though a microscopic description based on
electron quasiparticles fails, a tractable dual description based on the
"vortex of charge" is still possible. We construct a concrete example of such
strongly correlated bad metals where vortices are fermions with a Fermi
surface, and we demonstrate that its resistivity can be exceptionally large at
zero temperature. And when extra charge $\delta n_e$ is doped into the system
away from half-filling, a small Drude weight proportional to $(\delta n_e)^2$
will emerge in the optical conductivity .
