I know you're just dieing to hear what my opinion is. :)
Anyway, the line is crossed when you go from disseminating INFORMATION in that manner to spreading OPINIONS or LIES.
So, posting questions under various aliases and then answering them as yourself (or others) is fine. Provided that you are providing factual information.
BUT! When you are posting under aliases and are only posting your opinion (to make it seem that your opinion is widely shared??) or incorrect "information" (to counter correct information??) then you're on the wrong side.
I could also throw in "trolling" there. Posting inflammatory crap just to generate page hits for your site?