greasy spoon 
noun informal
A cheap, run-down cafe or restaurant serving fried foods.The brunch she cooked was little better than he could get at a greasy spoon or fast food restaurant....
- The new owner supplies food for the whole of the ‘eating-out-of-house sector’, from restaurants and hotels to greasy spoon cafes, buying and supplying the food.
- Gay venues are on the rise, particularly in Edinburgh; there are more gastropubs doing good food; fewer greasy spoons and bakers, but more and more tea rooms and coffee shops.