Results: Is it free or should I buy something?

OK so I need you guys to help settle something here. A local car wash place here offers free vacuums. My friend says that you have to get a car wash and that it's not right to take advantage of them. My argument is that if the sign says free it means FREE. It's not like there's fine print or a rule book anywhere. I also don't think it's a huge crime to simply vacuum your car. I often like to wash my car at home. The vacuums at places like this are very powerful and really get the job done. Also it's not like I don't support the place. I'll often buy cleaning supplies from the machines they have there. So please, once and for all settle the score.