“The sub picks the dom”
NO
No no no no no.
The sub and the dom pick each other. It has to be mutual! The asshole rando wannabe sub who sends unsolicited asks to a domme, calling her Mistress and blathering about how he’s under her control, is EXACTLY THE SAME as the asshole rando wannabe dom who sends unsolicited asks to a sub, declaring himself her master and issuing commands.
No one gets to unilaterally decide that a scene is about to happen. Unless everyone involved agrees to it, there is no scene.