I tend to make sweet/dessert things to take to 'bring-a-plate' do's... I notice most other people make salads etc, and I fancy myself as a pretty good 'sweet' cook (all that practice I do feeding my sweet tooth
lol) so I like to contribute to the dessert part of the meal...
I don't expect to bring any food home with me, if there are leftovers I just ask the host/ess to pop it into another container to keep in their fridge/share it around with everyone else to take home so I can get my plate back, that's all I worry about. It's a pain in the neck leaving plates at people's houses because inevitably it all gets jumbled up with their kitchen stuff and you never get it back, and I feel bad about leaving plates for someone else to wash up hahhaa
So yeah, if the host/ess says, 'Oh, there's some of this cake left, do you want to take it home with you?' I'm happy to do that, otherwise I just say, 'pop it on one of your plates and I'll take mine with me to save you the washing up'. If I want to get treats at home, I'll make up double batches of the slice/pie/cake/whatever and leave it at home for
DH and
DD to have the next day. I'd feel really rude about insisting on bringing any leftovers home with me, I leave it up to the host to offer.