Ah interesting 

The professional, “I can’t tell it like it is” way of saying - “you’re a fucking moron and what you’re doing is some of the dumbest shit I have heard this decade”

“I used scotch brite pads for a sealing surface on a motor”
“Ah interesting”

Ah interesting by Jtofjpn March 9, 2019

ainteresting

Not very interesting--used somewhat sarcastically, so that the listener believes you're saying "interesting," but you're really not. Derived from "ain't interesting."

Oh, sure, I'd love to watch your three-hour slideshow about your elementary school sock puppet club. How ainteresting!

ainteresting by bboxdw February 17, 2015