A friend of mine with a history of being rather self-centered was invited with her partner to my daughter's first birthday barbecue. Not only did she park on our shared driveway (whereas the other 30 guests realized it would be better to park on the street so as not to block the neighbors, including my elderly and not very mobile relatives) but she turned up with a bottle of wine.... and two wine glasses. She and her partner uncorked the bottle and shared the whole thing between themselves. Not only did they not offer any to anyone else, but to bring their own fancy glasses so they wouldn't have to drink out of a plastic cup seems pretty snobby! I found the bottle of wine in the kitchen afterwards and commented to my husband that at least they left the rest here for us.. but nope, the bottle was empty and they hadn't bothered to put it in the recycle bin on their short walk to the most selfish parking possible.
MY COMMENTS: I honestly don't see what these guests did wrong.
Ok, parking in the driveway might have been a bit inconsiderate, but what's wrong with bringing your own choice of wine and glasses to a BBQ? Here in Australia, the vast majority of BBQs (and house parties) specify that guests must bring their own alcohol.
Furthermore, guests don't have to bring enough to share with everyone - they just bring what THEY want to drink. And what's wrong with drinking out of proper wine glasses? Wine tastes better that way, and often glasses are more stable than plastic cups. I would certainly never criticise any of my friends if they brought their own glasses to drink out of - that's their choice, and I wouldn't see it as a personal attack on my hospitality.
Finally, I don't think the guests had to take their empty bottle to the recycling bin. It's the host's responsibility to clean up.