Set has a lot of demons gather around him. Most aren't pretty. Take, for instance, the toady-looking one that Set kills immediately after arriving in Phoenix: "[O]ne was short, squat, and hairless, with slimy skin that glistened in the starlight—like an amphibian standing on its hind legs" (6.7). Not exactly first-date material.
Set's other minions are no more pleasant. The longnecks, or serpopards, that come after the kids at the Brooklyn mansion are ferocious and dangerous. The carriers that are sent to put Carter and Sadie in a box look like they're made of metal, and are as hard to destroy as that implies. The Set animal (which Carter nicknames Leroy) is similarly freaky and scary and tough to beat. The various demons constructing Set's pyramid are also pretty freaky-looking: "massive blokes with the heads of insects, dragons, and assorted Swiss Army knife attachments" (36.81).
Take-home lesson: demons are icky.