The Roscoe Diner has definitely gone downhill.
If you turn the other way to go into Roscoe (it's a left if you're coming from the city) at the traffic light there's a restaurant called Raimondo's.
You can eat pizza, very inexpensively, or eat the slightly more pricey Italian entrees which are very good. Green salads are overly-chilled and under-dried-off iceberg lettuce, tomatoes, cukes and onions, but that's the only drawback.
Typical American portions, very large. You can share an entree, or be prepared to take food home with you. They serve wine and beer as well. The front room is more informal, with tables with plastic tablecloths (great if you brought the kids) and the back room is a more formal dining room. They get busy on weekends during the summer, though I've never needed a reservation to get a seat. You might want to call ahead if you have a large party.