When a guy compliments you...how do you know its genuine or he's being nice?

Ok, my guy friend always complains how all I wear are pants, and I never show off my legs. He said when he imagines me wearing a swimsuit or prancing around the house in skimpy outfits, all he can picture is pants. We argued over this forever. And he said he would stop all this once and for all if i sent him a picture of my legs. Well he is my best friend, and its just my legs, so I figured ok whatever. So I put on some short shorts, take a pic and shoot it over via text. I'm kinda self conscious about showing skin, so I was realllllly nervous. He replied back and said "You have really nice legs. Are you even wearing shorts?? It looks like some y undies instead ;-) They look really nice. I don't know why you don't wear skirts and shorts and show them off!". Was that an honest compliment, or was he just saying that to get me to wear shorts or be nice cause he bugged me to send him the picture??