[He's not much better, Dorian, but come on! You've got to keep up.]

It's disrespecting someone subtly. An example you might know from ye olden times is the American phrase "bless her heart." People use it to throw shade about someone being completely ridiculous or out of touch before explaining what they've done wrong. Elle does it beautifully with even more subtle and eloquent phrasing.

[It's truly a thing of beauty. He hopes Dorian gets to see it soon so he can see why he adores this woman.]