What does "greasy spoon" mean?

[Mickey]

English Language Tests, Intermediate level

ESL/EFL Test #719 "Real Life: Eating Out (2)", question 5

Let's go to the greasy ......... down the road from my place. I like little diners that serve fried food and prepare it really quickly.

(a) spike
(b) wheel
(c) spoon

English Language Tests, Intermediate level

ESL/EFL Test #719 "Real Life: Eating Out (2)", answer 5

Let's go to the greasy spoon down the road from my place. I like little diners that serve fried food and prepare it really quickly.

Correct answer: (c) spoon

Your answer was: correct
_________________________

What does "greasy spoon" mean in this sentence?

[Mister Micawber]

cheap, rather unclean restaurant
_________________
Native English teacher at Mister Micawber's