Curate, connect, and discover
Oh yeah, he is well aware that his face card never declines, he's got enough stories from the academy (and onward) to back that up
Its just that uh, he's pretty sure he's maxxed out his personality card and that it will, in fact, decline
of course I think Kallus has many insecurities but I DO think he knows he's pretty. I think he knows that people who are attracted to male humans tend to find him hot and I don't think he would look in a mirror and disagree with that.
and while he wouldn't be so sure how he might fit into Lasat beauty standards, I don't think he'd actually find it too surprising that Zeb considers him physically attractive. (it's just, y'know, the rest of him as a person he might struggle to believe Zeb likes or wants.)