"Here come Ernie and Hannah Abbott," said Ron, looking over his shoulder. "And those Ravenclaw blokes and Smith ... and no one looks very spotty."
Hermione looked alarmed.
"Never mind spots, the idiots can't come over here now, it'll look really suspicious - sit down!" she mouthed to Ernie and Hannah, gesturing frantically to them to rejoin the Hufflepuff table.
Harry Potter and the Order of the Phoenix
According to dictionaries, spotty:
someone who is spotty has small raised red marks on their skin, especially on their face
good only in some parts, but not in other parts
But none of them seems to fit for the context. What does it mean here?