First of all, don't buy precut bagged lettuce and spinach. Besides the bacteria factor, there are tons of other reasons why not to eat it.

Second, I definitely see the reasoning in the pro-meat peoples points in the meat vs. no meat argument. It doesn't make me want to go back to eating it, but I can respect and understand it. Rather than meat, I would argue the validity of us eating dairy products (self included on this one; though I don't actually drink milk I do consume some of the other stuff).

The argument on this one is usually "Well, where would we get calcium?" or "It's a good source of protein". The truth is there are lots of other much better sources of protein and calcium that we could eat if we so chose. Besides the fact of where does milk come from? A mother animal. Cows make milk for baby cows, ewes for baby goats, human females for human babies, and so on. So why are people drinking cows milk?
Point one, it's for a baby mammal, so once you are out of the baby stage you no longer need this sort of nourishment and move on to other foods. Second is that if you still could need it, and logic prevailed, that would mean we would be drinking breast milk for the rest of our lives.

*ring ring*

"Hello?"

"Hi, Mom? I was wondering if you were busy...I wanted to make some coffee."

"Uhm...well, could it wait till later, honey? I have to drive your grandma home. Do you want to say hi to her?"

"What's grandma doing there at this hour of the morning?"

"Oh, your father wanted a bowl of cereal for breakfast."