Here's a tip for Clothilde which I thought might save someone the frustration of trying to solve.
If you had prepared your clothing and your character in 2 seperate scenes and the collision detection just doesn't seem to work when you bring the 2 together, this might be the problem:
It seems as though the collision detection gets confused when you move it from, say, a 30FPS to a 25FPS environment. To fix the problem, simply set you cloting to its initial state to rest the clothes as they should be. Then remove all the collider and cloth tags and reapply them. This fixes the problem.
Hope someone can benefit from this.