In this paper, we present a comprehensive numerical study of the wavelength-dependence of transmission through sharp 90 degrees bends in metallic slot waveguides with sub-wavelength localization and varying geometrical parameters. In particular, it is demonstrated that increasing the plasmon wavelength results in a significant increase (up to nearly 100%) of transmission through the bend, combined with a reduction in the mode asymmetry in the second arm of the bend. The mode asymmetry and its relaxation are explained by interference of the transmitted mode with non-propagating and leaky modes generated at the bend. Comparison with the two-dimensional case of a metal-dielectric-metal waveguide is also conducted, showing significant differences for the slot waveguides based on the presence of different non-propagating and leaky modes.