  We have studied the kinetic roughening behavior of the fronts of coffee-ring
aggregates via extensive numerical simulations of the off-lattice model
considered for this context in [C.\ S.\ Dias {\it et al.}, Soft Matter {\bf
14}, 1903 (2018)]. This model describes ballistic aggregation of patchy
colloids and depends on a parameter $r_\mathrm{AB}$ which controls the affinity
of the two patches, A and B. Suitable boundary conditions allow us to elucidate
a discontinuous pinning-depinning transition at $r_\mathrm{AB}=0$, with the
front displaying intrinsic anomalous scaling, but with unusual exponent values
$\alpha \simeq 1.2$, $\alpha_{\rm loc} \simeq 0.5$, $\beta\simeq 1$, and
$z\simeq 1.2$. For $0<r_\mathrm{AB}\le 1$, comparison with simulations of
standard off-lattice ballistic deposition indicates the occurrence of a
morphological instability induced by the patch structure. As a result, we find
that the asymptotic morphological behavior is dominated by macroscopic shapes.
The intermediate time regime exhibits one-dimensional KPZ exponents for
$r_\mathrm{AB}> 0.01$ and the system suffers a strong crossover dominated by
the $r_\mathrm{AB}=0$ behavior for $r_\mathrm{AB}\le 0.01$. A detailed analysis
of correlation functions shows that the aggregate fronts are always in the
moving phase for $0<r_\mathrm{AB}\le 1$ and that their kinetic roughening
behavior is intrinsically anomalous for $r_\mathrm{AB}\le 0.01$.
