I am a runner, work out nut and health food junky *normally* but every now and then I get a hankerin' for a quarter pounder with cheese, fries and a coke. I just can't help myself. I also like Wendy's hamburgers. That said, if I eat a fast food hamburger I feel pretty nasty the rest of the day, like it has messed up my bio rhythm or something. Road trips aside I may get a fast food cheeseburger 2-3 times a year.
Actually, the egg McMuffin is not a terribly unhealthy breakfast as long as you don't get the hash browns. Their coffee isn't great IMO but it is better than any other fast food.