In "This Bird Has Flown", Lalo is the only one to notice that the drone isn't Sergio. Seeing as dogs have better sense of smell than humans, maybe he can tell by smell.
Ronnie Anne seems to be the only one in her family not to hate cats— in "The Horror Scope", she watches cat videos, while in "What's Love Gato Do with It?", her whole family admits to hating cats. This is likely because the Casagrandes have lived in Great Lakes City all their lives, and Maria has spent her childhood there, and in Great Lakes City, the cats seem to be extra aggro. Ronnie Anne, however, grew up in Royal Woods where the cats, while not perfect (see "Overnight Success", etc) are nowhere near as mean as the GLC cats. She's also best friends with Lincoln, so she might have gotten to know Cliff. This doesn't explain why Bobby (who also grew up in Royal Woods and is dating another of Cliff's owners) also hates cats, but it still bears consideration.
Sergio is pretty fastidious about his appearance and enjoys putting on flashy clothes. This makes sense, since male birds tend to be very showy and want to make themselves attractive to female birds.