I now just use coloured (colored for those in the USA) cable ties for my bags, securing them to a D-Ring if there is one. If not, I loop another tie around a handle or strap to make sure the bag can't be opened and resealed by sliding the zippers.

A quick check on collection will show if your bag has been tampered with - this has never happened to me since using the cable ties.

We all know that we shouldn't have anything of value in our checked baggage.