I believe that some of the products Dunkin Donuts tries to advertise and sell may impact their consumers. For example, I know I would never try the tuna fish on a croissant from Dunkin Donuts but I'll have a coffee, tea, bagel, doughnut or muffin form their anytime.
I believe it is part of the brand loyalty, but it can only go so far. If consumers are loyal to Dunkin Donuts, they will continues to go their regardless of their new products, as long as they keep the original.
I also agree that focusing the majority of their advertisement on their drinks is much more important since I mostly associate them with their coffee drinks. After all, American Run's on Dunkin, so I believe it is important for them to keep the image of caffeinated beverages up in hopes of keeping their current consumers and hopefully attracting more.