Shakespeare pokes fun at the exaggerated comparisons other poets use to flatter their lovers, insisting his mistress is nothing like those clichés. Her eyes aren’t dazzling suns, her lips are more pale than coral, her breasts are a dull brown, and her hair is like black wires. Her cheeks lack the blush of roses, and her breath doesn’t smell like perfume — it reeks. Even her voice falls short of music, and she walks heavily, not like a gliding goddess. The list builds a deliberately unflattering, earthy portrait.
But the closing couplet flips the tone. The speaker declares he finds his love as precious as any woman who’s been propped up by false comparisons. The mood starts out cheeky and irreverent, but shifts to something quietly sincere — an appreciation for realistic, unidealized affection. It’s a love poem that earns its tenderness by stripping away the flattery.