Google has likely implemented a new (or minimally upgraded) their review filter. It seems to trap many more good reviews than in the past. Usually these types of filters are "trainable". Google is interested in improving the filter by training it with examples of good reviews that have been caught so that it is less likely to do so in the future.
Also they have still not fixed the problems that they have with "losing" reviews. That always adds a bit of excitement to this mix.
I have been taking as many of these lost review cases as I can process to Google as I think it is total crap that so many reviews are being tagged. And I have been asking Google to review them. The problem I have is I can't tell whether a review is in fact spam. The only thing I like less than Google's approach are bs reviews. Also the many variables that might be triggering the filter are a state secret. As Jim pointed out it is likely that over time things will settle down and good reviews will be tagged less. If you haven't figured it out by now though the algo will be never 100% perfect and there is always some % of cases that it will handle poorly.
However, because of the way that the TC system works, it has been much easier to report to Google if you posted the problem in a new post.
But due to time constraints (and some fatigue dealing with this) I am going to suggest a new tactic.
Let's consolidate the issues into this ONE huge post and see if we can get someone from Google to monitor all of these cases. For this to work, I would need folks to go through the forum for the past month and ask that EVERY poster that is still having this problem post there specific case here.
If you are in, I will do what I can to get more Google eyes looking at this issue.