It isn't really that your questions have to be spectacular to avoid losing your privilege as much as it is about following the guidelines for asking questions. Following the guidelines will allow your question to be well received.
What revokes your asking privilege is when these guidelines are not followed (they can be found in the relative exchange's help center), and the result is that your questions are either closed, downvoted, deleted, or all of those. When a majority of the content provided by a user ends up in those categories, especially the deleted category, then their privileges can be revoked.
Generally speaking, your question will be well received if
- The answer is not easily found with a simple google search
- The question is not a duplicate of another question
- The misunderstanding or confusion you are having is well explained and as brief as possible for the given context.
- There is reasonable solution or obtainable goal that someone can explain in an answer
And you will avoid the question ban if
- Your question is well received
- You fix the question when there is something wrong with it
- You are attentive to users pointing out issues with the post
- You avoid deleting your question instead of improving it (important)