To use shader in one of your projects append from the File menu and click on append name of the blend file is glass imperfections.blend.

Overview of shader settings:

1. Surface imperfections scale: Adjusts the size of the surface imperfections.
2. Smudges amount: Adjusts the amount of smudges.
3. Smudges scale: Adjusts the scale of the smudges.
4. Smudges detail: Adjusts the detail level of the smudges.
5. Surface imperfection amount: Adjusts the amount of surface imperfections
6. bump map strength: Adjusts the strength of the procedural normal map to further improve realism.
7. IOR: Allows you to change the IOR value of the glass.
8. Color: Allows you to change the color of the glass.