On Stack Exchange, somebody asked for tips for posting civil and informative comments. This was my advice:
Another way to make a comment more friendly is, when possible, to cast it as a question rather than a statement. Consider the difference between:
- (Answer) doesn't work because of X.
- When you do that, how do you account for the problem of X?
It could well be that X isn't a problem -- your assumption is wrong. If you assert it you look bad; if you raise the question the poster isn't put on the defensive, and if it's a problem he can fix it (and thank you for the help).
I used to leave comments like the following that I thought were friendly and helpful:
- This question/answer could be improved by adding (details/a source).
I realized that comments like the following got better results and also that I preferred them when on the receiving end:
Could you add more details about X?
Do you have a source?
This approach doesn't always work (e.g. for site policy). It's also most important for the initial comment, before you and the other person are engaged in a dialogue.