Haha, I like this one, because it really depends on how the person says it. Attitude is everything. If they are happy, like "Hey, I'm new here and hoping to find a tasty dinner. Are there any good restaurants in this town?" then yes, the person really wants to know where a good place to eat is. If they are more angry or annoyed (usually marked by word emphasis), like "Are there ANY good restaurants in this town?!" then odds are they have just eaten another meal they didn't like, and are frustrated with the quality of every restaurant they've been to. Grammatically, on the page, they are exactly the same.

This is quite a funny question. It definitely depends on the tone you use and what you stress. Emphasising "any" makes it more negative and emphasising "good" makes it sound more positive. A less ambiguous/more friendly way to ask the same thing would be to say: "Do you know of any good restaurants in this town?" To ask a more direct question with the other potential meaning you could say: "Are there any good restaurants in this town at all?"