Lowest grade restaurant you ever ate at?

[ChrisGlass]

Here in Los Angeles County, all places that serve food must place in the window a letter rating by the Health Board.
99% are 'A'
Seeing a B is like a rare occurance, usually KFCs and Taco Bells.

I've heard of a mexican sit-down place that got a C.

What's the lowest you'd go? I mean, I ate at a KFC that had a B and didn't shit blood, so I consider that a win.