1. Postings that are more advertising than informational, which I briefly commented on here: http://news.ycombinator.com/item?id=4350447; and
2. Members who submit their own postings.
Briefly, while I appreciate the sharing of information, any content that becomes an obvious sales pitch doesn't belong on this site. When I read a posting from this site, I want to learn and be informed - I do not want be sold on something. And - there may be disagreement with my second point - I do not find any significant value when a member submits their own positing, because I feel they're trying to sell me on something. (Please understand this does not apply to "Show HN" - just to articles and blog postings.)
Overall, I really appreciate members asking for feedback on their projects. They should be challenged and not degraded or insulted. This is a great community with great insights, so it's up to everyone to be "good neighbors".