I'm going to give someone a dirty look for being gross
In what way do you feel that they were gross? Was it something about their appearance?
They carried food while using the elevator. I find it disgusting.
Maybe you should take the stairs if something like that bothers you. Unfortunately since the elevator is for everyone, the general public will use it as well.
It's my business, when someones doing something that is making me sick. I'm going to tell them how I feel about it.
I understand how you feel, it can be frustrating to have to share an area with people we don't approve of. I think taking the stairs would be the best option because you will not have to share a tight elevator space with someone you find objectionable.