I am a sort-of vegetarian. I don't eat mammals. I had to expand from "no red meat" to "no mammals" since pork is technically "the other white meat" but is still a mammal that I have no interest in eating. I began limiting my diet back in high school. I gradually cut back on meats, even trying full vegetarianism. Due somewhat to parental protests, I agreed to keep eating chicken and other poultry and seafood.
I can't remember anyone complimenting me on my choice to not eat mammals. The closest thing to a compliment has come from others who limit their meat intake, and even some of those don't understand why I only eliminate mammals from my diet. I used to try to explain it to nearly everyone who sneered at my choice or told me it was weird. I've stopped doing that, for the most part, unless I sense they are truly curious and not just critical because they'd eaten six burgers that day.
I do it partially for humane reasons. It doesn't take much searching to uncover the cruelties commonly forced on animals bred for slaughter. Electric prods, unnaturally altered diets, confined living quarters: it's all so unnatural. Do I love my burger enough to put another living being through unnecessary pain and growth hormones? No. I'd also like to add that, although I will still eat poultry or fish, I do my best to find hormone-free, free range, non-farm raised, etc. I'm lucky to live in Ohio in this respect, the Amish raise some darn tasty natural chicken.
The other part of my reasoning is health related. Red meat just isn't that good for you. People with high cholesterol and other diseases are instructed to cut it out of their diets. The chemicals used to treat meats practically carcinogenic. People who don't eat red meat live an average of two years longer than their carnivorous counterparts. Not to mention digestion. The human body is not designed to digest red meat. It gets to your intestines, sits there, and rots until it can be processed. Yum? I'm out to have the flattest, leanest belly that I can, and having food sitting in my intestines for long periods of time doesn't sound like a great contributor to that cause. It is high in protein, so I have to find that elsewhere, but the fat content is worth the trade.
Not to mention the quality of commercially prepared meat products. Taco Bell faced a class-action lawsuit over their "ground beef product" which claimed that what they were selling as beef contained less than the USDA standard of 40% meat. The lawsuit was later dropped, but it brought to my attention that the government required something to be only 40% meat in order to be marketed as "meat." I don't know about you, but I'd like to know what I'm eating and you can bet that there are some gray areas in that other 60% that may or may not be good for a human body in the long run.
Long story short, I think I have pretty good cause for not eating mammals. "Because it tastes good" isn't cause enough for me to ignore all the evidence again red meat, particularly. I don't try to convert anyone to my way of eating, nor do I expect people to abstain from burgers around me. I just choose not to eat them. I don't talk about it unless asked.