You make a mere quantitative distinction. If a person has bad vision and corrects them with contact lenses, their kids will likely have bad vision and need contact lenses too. If a person has a severe overbite and corrects it with orthodonture (which takes longer than leg lengthening and also involves suffering), chances are their kids will have a severe overbite and need orthodonture. They're falsely advertising good vision and good teeth. Same with height; the kids of a genetically short guy are going to be short, and if they want to be taller they'll need a procedure.