Similar to this question, suppose there is a chain of restaurants that is mostly non-Kosher, but there happens to be one kosher franchise in the chain. The example I am thinking of is that there is one kosher Dunkin Donuts near where I live, and many non-kosher ones. Is there a problem of Maris Ayin for me to publicly carry around a Dunkin Donuts bag from the kosher store?
If the answer to that is that there is no problem, what about if I pick up a donut on the way to a business trip out of town where there is no kosher Dunkin Donuts? May I carry the bag around there?