Exactly Denis ,
that' s why I donate my used ones after the hunting season . They aren' t permanent , but can provide reasonable scent control for about 2 weeks from my experience . The last buck I shot at was about 20 yds from me while I was wearing a suit that hadn' t been rinsed out since I prepared it for the season(2 weeks) . The wind was in his favor , so I' d have to say the suit had some effect in that case .

I do descent as much as possible before going out , and I dress in the field to avoid contaminating my hunting clothes .