I made a cup with a glass by setting transmission to 1 and roughness to 0. So I somewhat made it like above. However, As you can see if you zoom in it. there are several points to improve such as smudges on the glass or some artifact border along the side of the cup.
I'm using blender 2.80.75 and Cycles with GPU computed device and in the view layer, I'm using also Denoising Data feature with the default setting.
How can I fix this? I also have googled this, but couldn't find what I want that remove artifacts and smudges.