Is it bad when guest takes more food and dont left for others

Yes. But it depends on the person and the size of their family. If the reception has 20 kids and takes home the companies left over party food. I don't care.

I think it's fine , as long as the party or whatever is over , and you or they ask permission.

It's rude. But a host should always try to have extra food and drinks.

That's crazy if you ran out of food for guests.