Nice system 4-2-7 but I don't see how it has anything to do with the Pro-Ject tables.
Reputation of a product is not only based on what the people who own one think about it, but also what people who have no experience with the table think. The latter have no basis for their opinion other than what they have read and gathered from that. Then these people spread their selective opinion with no first hand experience and things escalate. What would be interesting to hear is the opinion and experience of someone who actually has a lot of experience with Pro-Ject tables, like knowledgeable dealers who have set up a lot of these tables, their experience should actually tell something about how common or rare the hum issue for example is.
Probably the issue is/was somewhat common, because there's been enough reports that we now get claims like 50/50 chance - I suppose technically there's always a 50/50 chance, because when you buy something it either works like it should or doesn't...

I have no idea on the actual numbers but I highly doubt 50% of the tables have been with issues. For one thing I've never read a review of any Pro-Ject table that mentioned such issues, but of course it's always possible the tables for reviews were cherry picked, depending where the reviewer got his sample from.
Also forums are generally negatively biased in cases like this - no problems is no news, so people generally don't go around the internet posting "I bought a new turntable and it has no issues" but turn to forums when they think there might be something wrong.
Just trying to provide some perspective because it seems discussions about Pro-Ject (and certain other brands) usually get very polarized here. The general opinion on Audiokarma regarding Pro-Ject tables seems very negative (apart from owners, most of whom actually seem pretty happy) comparing to other forums I frequently read.
Anyway, by now hopefully the issues have been fixed and potential buyers are aware of them, so that if there indeed is problems they know what's going on and know to take the table back.