Using a S300C as an example, with a main rotor that turns CCW when viewed from above, the tail rotor creates thrust to the right. Slope landings require lateral cyclic and the amount of lateral cyclic available can determine the steepness of slope you can land on. By holding in left cyclic to counteract translating tendency we are using up some the left lateral cyclic, leaving less cyclic travel for the actual slope work on a slope that slopes down from left to right. On a slope that slopes down from right to left the translating tendency helps to hold in the upslope skip and more cyclic travel is available to keep the skip into the slope. A steeper slope can be landed on if it slopes downward from right to left for a S300C or similar helicopters.