Now that we are seeing the new Blogger commenting system rolled out through the majority of our blogs, some bloggers are seeing problems with the "spam" / "not spam" classification of some comments. While the training process is in progress, and the system is still "learning" which comments are spam - and which are not spam, we are going to see some legitimate comments dropped into the "Spam" folder. We will similarly continue to see some spam comments published (with moderation not enabled), or dropped into the "Awaiting Moderation" folder (with moderation enabled).
Until the system has "learned" your standards, you would do well to moderate comments for a while (even if that's not your personal preference). Periodically, scan through the "Published", "Awaiting Moderation" and "Spam" folders, looking for comments which are in the wrong folder. In the first two folders, check and select "Spam" for those comments which you consider spam. In the latter folder, check and select "Not Spam" for those comments which you do not consider to be spam.
If you find your self significantly disagreeing with the system, as to which folders your various incoming comments are being dropped into, continue to scan, and correct. Only, by your doing this, will the system learn your personal standards. If you stop moderation, and continue to find comments that are being mis classified, according to your standards, you have only yourself to blame.
Just remember, the new system is not optional. Everybody has to work together, to make it work. And we need to moderate sooner, not later.