When modifying an adjective like good,�any� is an adverb of degree (to determine whether some property or characteristic is greater or less than would be considered typical). It�s the equivalent of �at all�.

 

As for finding "natural contexts" for your modals, why don�t you have a look at some of the available text corpora such as the British National Corpus (BNC) or the Corpus of Contemporary American English (COCA)? You�ll find the modals you�re after in authentic contexts (�concordances�).

To add to Alex�s answer, we use "any" in questions when we expect a negative answer, or don�t know what kind of answer to expect. With that in mind, "Are they any good?" can be mildly insulting as compared to the neutral "Are they good?". However, this particular question usually doesn�t have a negative connotation, and is the most common way of asking about the quality of something.

 

In contrast, if your friend bought something advertised on television, you might ask, "Is it any good?", definitely meaning to imply that you don�t expect it to be very good. That implication is avoided if you ask, "Is it good?".

 

Bruce