If somebody says that you’re a looker, you should definitely be flattered—they are paying you the ultimate compliment and saying that they think you’re good looking. They’ll probably never say it to your face but you could hear it from someone else.       

Example 1)

“That Marni girl is a real looker don’t you think?”

“She’s a nice girl but not my type!”

Example 2)

“Have you seen the new history professor yet?”

“No, but I hear he’s a real looker!”

“You hear right. He is!”