So when someone offers me a burger and I say - no thanks - They say "Oh are you a vegatarian"... The above ^^^ disseratation seems rather lenthy
See, my response to this would simply be "nope" with a smile. I don't see that I need to define myself to anyone. If they pressed for more information, I'd say something like "there are some things I don't eat, and some things I do."
People tend to think that it's ok to just ask any old personal question and to delve into your whys and wherefores ... and I just don't buy into that. Not that I consider what you eat to be on the same level as, say, your sex life or your finances!
But mostly unless someone is asking because they're really interested in getting to know me or interested in the lifestyle I've chosen, I just smile and keep my answers short and sweet.