On a slice, the angle of sidespin is directly related to the height of the ball at the strikezone.
As a lefty, on low balls, my slices skid severely to the right at the bounce.
On medium high balls, waist to chest, it's almost all backspin with some sidespin to the right.
On higher balls, those over my shoulders, the ball curves and bounces to my LEFT, like a rightie slice serve.
Reverse the curve directions for righties, but the medium high ball is mostly backspin with a little bit of side.