Sandstone stairs and slabs, smooth sandstone stairs and slabs, red sandstone stairs and slabs and red smooth sandstone stairs and slabs are all darker than other blocks, with blocks above them or not, day and night, in any climate, the difference is visible, just put an sandstone stair and an sandstone block side by side and see the difference. The stair/slab looks like it doesn't belong there, they have an permanent "shadow" around them, it completely destroys any sense of building integrity, it's an ugly glitch that has been in the game for too long.