However, in an ideal, polite society, everyone at the party (whether they know about the non-beefeaters or not) would look at the big plate of beef dogs and the small plate of chicken dogs and make the logical, thoughtful conclusion that those chicken dogs are probably for someone specific. In their uncertainty, perfectly polite folks would ask.
How does anyone know who those specific people are though? If someone prefers to not eat beef aren't they part of that specific group? How are they to know that their preference (whether its a general preference or just what they prefer at that moment) wasn't the one one being catered too?
You missed the part of my post where I said:
Let's pretend that we're not talking about tofu. Let's pretend that we're talking about halal or kosher chicken dogs in a room where there are 3 people who cannot eat beef for religious reasons. There is a big plate of beef hotdogs and a small plate of 6 chicken hotdogs. There are enough for 2 hotdogs for everyone. The beef-eaters choose the chicken dogs because they are super yummy. This leaves one hotdog each for the 3 people who abstain from beef for religious reasons.
Two of the beefeaters who took a chicken dog know that there are people who choose to abstain from beef in attendance. One of the beefeaters does not know.
The beefeaters who know about the non-beefeaters may nto be outright rude, but they are definitely being extremely inconsiderate. The one who does NOT know why there are chicken dogs is being neither rude nor inconsiderate.
It was a long post, and that part was probably easily lost in the wall of words - I tend to ramble sometimes.

So if you
don't know that there are vegetarians present and you eat the yummy vegetarian dish because it's yummy, you're neither rude nor inconsiderate. If you notice that it is a specifically vegetarian main dish and there is less of that main dish than of the other main dishes, AND it's a main dish that's comparable to the non-veggie main dishes (ie veggie dogs or veggie burgers when there are loads more regular dogs and burgers), it would be
more considerate to stop and thing about whether this is meant for someone specific, and maybe do a quick check.
But if you really don't know or didn't realize that any of your friends are vegetarian (lots of us like to keep it low key to avoid the preachy feeling that comes with explaining our choice and avoid coming off as snobby or 'picky' as you earlier mentioned), if you really thought this was just something different that the host/ess has offered, and/or if it really didn't occur to you that this might be a main dish for a specific small group, you're neither rude nor inconsiderate.
It seemed to me in the original post that the person who took the veggie option
did know. That may not be rude, but it is pretty inconsiderate. It's a subtle difference.
Also, it seems likely to me that at a party of 20-30 guests, most people are going to know each other. I know I can easily pack my house full of 30 people who all know each other to some degree or another.
