I upvote every question where I partition in the challenge, because I think a good question is a question which attracts my interest. The only exception is, when I like the challenge very much, but the question is poorly worked out:
- unclear from the language
- no examples provided
- questions about border cases don't get answered
- poor layout
In the above cases, I even might downvote the question.
In contrast, I upvote a question even if I don't take part in the challenge, if it is worked out very good:
- test cases, examples
- clear language, border cases catched
- maybe: images to illustrate something
- proper layout
- interesting challenge, but maybe too hard, too exotic for me
The language problem and border-cases can be solved by asking for assistance in chat or in the preparation-thread on meta - nobody will steal your question; I guess that is the common sense of fairness here.
It is annoying to start in a challenge, and, because of an unclear question, to restart from scratch, to solve the changing puzzle.