Kashrus supervision aside, I do not eat from DD for a number of reasons including Cholov Yisrael, Pas Palter and Pas Cholov. But that is my hangup. Others can feel free eating there because:
1. Cholov Yisrael – Rav Moshe, the posek hador permits Cholov Stam. Further, the Har Tzvi says that one can use regular powder milk (the primary dairy ingredient in the donuts)and it is even less of a kulah than the Rama’s kula for cheese and butter.
2. Pas Palter – Most poskim agree that pas palter is only me-akev during aseres yemai teshuva. Some are more machmir on shabbos but during the week yesh al mi lismoch.
3. Pas Cholov – If you stay away from the croissants and bagels most poskim are not makpid for pas cholov when eating mezonos. (My posek is.)
And while I don’t eat in these places the mashgichim can and do inspect the stores seven days a week including Pesach. If you think that a store owned by a shomer shabbos is not susceptible to employee (or chas veshalom propreitor shaningans)you are fooling yourself.