rabbiofberlin
and why do you assume that the maaris ayin aspect is less in starbucks than mcdonalds, if both serve treif hot meat sandwiches?
I hope the Rabbi doesn’t mind if I answer for him.
Mcdonalds’ primary business is to sell tarfus, so it’s an issue of maris ayin to go in even to buy a soda or coffee; one would naturally assume that the intent is to buy a hamburger. On the other hand, Starbucks’ main product is coffee, so despite the fact that one can also purchase tarfus, it’s not an issue of maris ayin (assuming the coffee is kosher, obviously).
It’s not appreciably different than walking into an Shoprite to buy kosher food, despite the fact that there is much non-kosher food sold as well.