Using Rose as a honeypot sounds extremely inefficient, but what else could the family do? The movie clearly establishes that they've got to get those people to their house somehow, and it's not like they can simply abduct anyone on the street.
Except ... wait, that's exactly what they can do.
The man in the picture above is Andre. Andre is nabbed while wandering around an upscale suburban neighborhood, presumably looking for an Olive Garden. Rose's brother, Jeremy, lacks his sister's bubbly charm, so he apparently knocks out random black pedestrians and stuffs them in his car.
And it's not like Jeremy's method is any less successful than Rose's. Andre was clearly hypnotized, brain-transplanted, and sold with no real problems. Jeremy achieved in a single night what took Rose five full months.
On top of all of that, Jeremy's method is significantly safer. While she was dating Chris for half a year, she met all the people in his life -- like his friend, Rod, who might wonder why his friend didn't come back from her house. A bisexual girl who dates only black people is already going to generate some gossip, but if every single one of those people mysteriously goes missing, it's safe to say that story would get picked up sooner or later. And a string of abductions linked to the city's most famous interracial sex addict is a much easier crime to solve than a few seemingly unrelated disappearances.