Dirty clothes do nothing to disguise electronic items and jewelry if the airport employees (TSA, security) are using xrays.

Dirty clothes, especially in a 'classy' bag do nothing to deter a thief with unsupervised time on his hands. The locks can be easily and quickly picked and practiced thieves are on to the 'dirty clothes' trick.

I am surprised that the lock was relocked. If the zippers are nylon, I think it's possible that the thieves opened and resealed them. You can avoid that by making sure the lock is secured to another part of the bag that prevents it from sliding around freely.

At the end of the day, there's really no effective way to guarantee your bag and its contents will arrive unmolested. (I recall somewhere, NYC, I think, where they found piles of opened and pilfered bags in a vacant lot near the airport).

Very sorry this happened to you.