I was never a big meat eater, but I became a vegetarian over the summer, following an externship with USDA APHIS.
I would probably eat meat, and poultry, if I knew exactly where the meal was coming from, and how the animal was killed.
I didn't see large production facilities, with APHIS, rather, small mom-'n-pop slaughter operations, and some were better than others.
My personal feeling is, I don't want the animal to see other animals being killed - right before its time of slaughter, and, I want the animal to die as quickly and painlessly as possible, and ideally, to have some semblance of a balanced life beforehand. If I could have that knowledge before putting the fork in my mouth, OK. But until I have reliable access to that kind of meal, I haven't eaten meat.
It's been very hard for me not to eat chicken - as I ate so much of it before. And I still eat cheese, and will use regular milk in my coffee (otherwise been using lots of soymilk for cereal, etc.) I understand what others have said about the quality of life issue for dairy cows and chickens - but I confess I'm not good enough with food prep and diet and time to exclude eggs and cheese right now. My brother has been the same for longer than I, and although I would still eat fish, he doesn't, but more-so for taste.
Becoming a vegetarian has instilled in me even stronger feelings of respect and/or the knowledge that we need good food animal veterinarians and safety measures for the animal food supply. I know people are not going to stop eating meat (or eggs, milk, etc). With that thought in mind, safety and welfare are important to me.