but we also need to be sure that the one we are reporting are real spammers because sometimes those people who are innocent are the one who is being reported so we should consider first in reviewing their acc and their past post if they are really worth to be reported..
What are you saying? You sound like someone who haven't used the report to moderator button before. If you click on the button you'll see something like this
You have reported ** posts with **% accuracy (** good, ** bad, **unhandled).
The ** was use to replace actually numbers in the quote above. That means for each post you report and they're seen as good posts, it won't be deleted and I'll reflect on your report page as a bad report. So it does no harm to the OP. In conclusion reporting an innocent people (as you said) , it does no harm to them. And if their posts was a quality one, it won't be deleted instead you'll be the one having bad report record.