Bedbugs may come from filth but they are carried by people who are not filthy but who do things like put their purse down in a theatre
Dogs (trained) are the most effective means to find infestation.
Even have knowledge of an infestation inside a lap top computer. Sixty minutes in a 175 degree oven worked well to stop that infestation from spreading. Computer was fine.
Any idea how you train a dog to find bedbugs?