TBH, I've never really thought about it! Just thinking back on past experiences though, I've always split up the leftovers between the people who are still there when I start clearing, so everyone gets a bit. But if they've come over for dinner and I've made it all, I do put it all in my fridge, because we'll use it for work the next day.

I know when my aunt used to have big parties, she would encourage everyone to take their plates, including anything on them, when they left - it just got rid of the hassle of trying to find original owners!

Interesting question!