This is crucial life advice. If your cocktail comes out opaque or bright neon pink, it’s been ruined by a bad ratio or cheap syrup. A proper Cosmo should be translucent, like a jewel you can see through.
Also, taste it. If it tastes like cough syrup, they used sweetened cranberry juice. If it’s too sour, they forgot the triple sec. A perfect Cosmo should make you say, “Oh, that’s nice,” followed by a little shiver.