There are something like 80 thousand muslims in Dearborn which is a lot and they can be a problem but its anything but a no go area. Dearborn is one of the most economically stable Detroit suburbs because they rely on outside business. The majority of their business comes from the million or so middle eastern Christians who also live in the greater Detroit area.
Unfortunately some can't get around the idea that arabic writing does not equal muslim. Virtually every Coptic, Chaldean, Assyrian, etc have signs that include arabic. Some Christian women in the area also wear head coverings as a habitual cultural style thing.
Here is a photo of an Assyrian church with lettering in both English and Arabic.
In simple terms, there are problems with having that many muslims in one place but Dearborn is not dangerous. Plus, the overall number of muslims is falling in comparison to the Christians as the muslims head south and west. Michigan has fallen to 7th or 8th on the list of muslims per capita by state.