I think what needs to be taken from that is that eating food you find in bins is always risky and if you're going to do it, you have to accept the risk.
Take me, I tend to be more careful than most of my friends who skip. I only eat stuff that has either been cooked in a way that should kill off any nasty germs, or stuff that comes to the business pre-packaged. The sandwiches I mentioned in my last post are a good example of this - there is a place near me that clearly buys far more sandwiches than it sells, and so there is often bags full of them, in their own individual packaging, in dumpsters separate from where the regular food goes.
Maybe I've been lucky, I don't know. I don't tend to do it that often - I only really do it when I am with a group of people who are going to do it anyway* or because I am part of an event where other people who are participating in it may not have easy access to food.
*This doesn't really apply to me, but as an aside, for rather a large number of people I know, skipping really isn't avoidable. They don't (primarily) because it is "good for the environment" or because "fuck corporations!", they do it for a much more simple reason than that: if they don't get food out of bins, they don't get it out of anywhere; their poverty makes it a 'choice' between the certainty of not having enough food to eat, and the chance of catching a stomach bug.