Of course. Sentient robots are mostly a charming bunch.
Astroboy = well liked
Chii = fairly charming
Cyber Girl Mahoro = my wife says she's charming
The Vision = scored with the Scarlet Witch
the Tachikomas = downright adorable
Bender = maybe not charming, but definitely persuasive
Commander Data = the exception that proves the rule
Lore = Aside from the whole bit about killing people, who wouldn't rather hang out with Lore than Data? Charming.
Seriously, I'll take a look at the code. It's probably just that there's no modifier to Charm, but you need to make an exceptional roll just to get the robot sentient in the first place.