Where should we draw the line between spam and market research and reasonable questions? C.v. this question
Is it ok to:
Say "Hey is there a market for my product http://example", thus requiring people to visit the page to find out what it is about? Clearly no, I think.
Give some glowing marketing statements, without much content, and point to your app and ask if it is good? That's how I'd categorize the example above, and I see it as spam.
Describe a real technical need, and a technical solution, and point to your app as an example, with a price point? That sounds like actual market research, but not the sort of thing I want folks to be doing here - it will typically be conflict-of-interest and subjective as to how well the app meets the needs.
List some products, including yours, and ask which is best? At least that helps put things in perspective, and invites more comparisons, but even that would need some guidelines to not be "subjective" and those guidelines run the risk of people with a conflict-of-interest putting up rigged requirements that highlight their particular option.
insert your effective guidelines for to asking generally helpful market research questions here
On the plus side of most of these, I'll just note that we do need to get more questions on this site....
Note that our current faq on this simply says:
Marketing/Spam - This is not a site for posting marketing spam. If your product/service really does what the question asks for, please caveat your answer as others may not consider it 100% objective.