To me, a big factor that I subconsciously evaluate on is the "fakeness" of the appearance itself. Instances where plastic surgery results in the uncanny valley of "should be good but looks too perfect or messes up a critical aspect" disturb me. Plastic surgery isn't as powerful as Photoshop. Maybe that's more on the surgeon, and subjective criterion of attraction (such as mine), but it simply isn't the case that plastic surgery makes someone look good.