Color amplification is real: a swatch that looks like a gentle beige on a 2-inch chip can read as a strong tan when it covers all four walls. Always go one shade lighter than your favorite chip.
Surrounding context matters. The same gray will look warm next to cool blue tile and cool next to warm oak flooring. Test the paint in the actual room with the actual finishes already in place.
Sheen also changes perception. The same color in matte vs. eggshell vs. semi-gloss will look like three slightly different colors because of how each finish reflects light.