if something isn't lycra, pvc, or rubber, it shouldn't really stretch.  lots of clothes today do have some lycra or spandex in them, for cleaner lines when draping, so you do need to use judgment.  set your stretch resistance higher if you get too much stretching.  i personally like somewhere near 200 or so for no stretching.  and if you want something to stretch in places but not others, make more than one dynamic group.  also, you can increase static and dynamic friction to prevent slipping.  really, though, there ought to be a "tightness" dial.  something to control the initial tension of the fit on the figure.  i keep wondering where i could make that suggestion, because i think it would be possible and greatly improve cloth room performance.