As you know, I don't eat meat except when it's an ethnic food I've never/rarely had and really want to explore (i.e., my "cultural exception"). It was the only way I could balance my interest in (a) changing my environmentally damaging consumption patterns but (b) retaining my ability to explore, in an experiential way (as opposed to intellectually and academically, where I already have 30+ books on food history and sociology, and this is on top of any recipe books I have), ethnographic food trends.

To my friends, I explain the whole situation. But, lately, to people I will never encounter again---for instance, at restaurants---I do occasionally use "vegetarian" as a shorthand, much as you might be annoyed at me for that. For the very reason you describe---I don't want people sneaking little bits of chicken/fish/meat/egg/etc into my food when I'm trying to avoid meat or telling me "it's just a little bit". But that is far more likely to happen if I explain "I don't eat meat except for certain cultural exceptions" because this far too difficult for many people to get, on a surface level. Believe me, I understand your concerns about this shorthand making it difficult for people who never ever ever eat meat. But I think by limiting it to people who I'd never encounter again, that's avoided, because those people would never see any non-"vegetarian" behavior of mine in the first place. And I think it probably helps the concerns of "true vegetarians" by raising the percieved demand for vegetarian food.