It is true. Beef, for sure. Chicken, well they do wash chicken in bleach so the chlorine kills most of the salmonella from feces. This is why you must always wash meat before you cook it.

Vegetables - well, they every so often recall veggies because animals shit in the field, and maybe the illegals labor too. I remember several e coli based recalls.

I wash my produce in grapefuit seed extract solution because it is non poisonous but it kills bacteria. Used all around the world for this commercially.

The only times I got salmonella poisoning were when I ate out.