If there was some kind of afterlife, I knew my asshole father was staring down at me, snickering and stroking a bald cat like a cliche evil villain,

Nice imagery and voice.

as I power walked into my own intervention.

No idea is this means? Is this metaphysical, or if she literally power walking somewhere?

Marcia sat with her hands clasped in her lap and the guilty smile of a dog who stole the roast off the counter. Thin baby hairs frayed from her tight bun, a bootleg halo framing her well-lined face. With a sigh, I set down my sweating cup of iced coffee on her desk. The Dunkin logo looked like it was crying.

We're getting white room syndrome. The rest of the 300 words is basically dialogue. I have no idea where your 2 characters are besides that there is a desk in this room. Or maybe it's not even a room. She could be outside on a desk on a porch overlooking a beach.

What is this Dunkin logo and does it look like? I can't imagine it crying if I don't even know what it is that is crying? Is it their company logo? Is it another company's logo like a Starbucks up? Or are you talking the Dunkin Donuts logo? But logo doesn't have a face to cry.

Instead of spending 2 long sentences on Marcia's description, I think you need to expand on these other points I've made.

“Were there any issues with the listing?” I asked, giving her the benefit of the doubt. I stole a glance over my shoulder —no hand-painted banner, thankfully— before balancing on the contour of the leather chair across from her.

Em dashes in American conventions are usually written with no space before or after them. In British conventions (I think) or journalism (I think), em dashes are more common with a space before and after them.