The right lighting to see where I need to add some joint compound.
"Critical lighting" is a drywall man's worst enemy. Sounds like you have a light(s) that shines directly on the joints you're seeing. "Down lights" (cans) are often an issue as they project the light in a direction. Any halogen lighting is even worse. They are more direct than everyday sunlight or most surface mounted, incandescent ceiling fixtures that "wash" the wall with light. Paint with any kind of "gloss" also exaggerates the issue. I've seen issues with "sunshine" causing the problem when a swimming pool reflects the light into the house (intensifies the light) and all of the joints show in the room. IF the lighting is the issue, even skimming the joints will likely not solve the problem. The finished joint is actually smoother than the paper face on the drywall and lighting will show that difference. The only thing that will solve the problem is to "glaze" coat the entire surface with compound, sand, and repaint (called a level 5 finish). Just my guess....
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