I actually don't think the burgers are horribly greasy--a little bit so, but not a ton more than any other burger (except for McDonald's, whose burgers are not greasy because they're made out of cardboard, apparently). It's really the fries that are greasy, plus it seems like there is aerosolized grease in the air of the store.

Someday I will have to do an experiment: get a burger only (no fries) to go and have someone else go in the store and pick it up...and then see if I feel like I am covered in grease after eating the burger. To date, I have not done that experiment bceause a) since the burger is best appreciated fresh, I always eat in, and b) if I'm going to plan to die early of a heart attack by eating a Five Guys burger, then I might as well enjoy the experience fully and go all-in and have some cajun fries, too. Thus, I always eat in and get a side of fries, and I always then feel like I've taken a bath in their fryer when I leave...