I'm probably not the best example, I too have eaten both these things....as long as they look fresh. I've only stayed away from premade at cafe's if it looks like it's been sitting a while and a bit stale.

As for what I make at home, I just make sure the pre-packaged lettuce is washed - I mean, how different can it be from a whole lettuce, they don't add anything to it...

I agree with webbmeg, I think you can be too careful and drive yourself nuts with what you can and can't eat.