Just try posting something that breaks the rules, and see whether it actually appears.
Sometimes things get through, and you see a "Rejected by moderator" on the thread, but normally they just don't get through.
It just shows that the Register has dedicated moderators.
My bug-bear is that sometimes, when I post something that I don't think breaks the rules, I still get a post rejected, and I cannot find out which of the rules the moderator thinks I broke. I know it is down to the moderator and their decision is final, but just a single "Rejected because of rule X" would be useful. I had a public exchange with Sarah about this on the comments thread of the news item announcing the rules.
And I have one recent post (which was critical of the Reg. using an inappropriate stock picture appearing on the revolving marquee headline) that did not appear, and was eventually rejected, but it took two weeks for it to be rejected. Strangely, for that two week period, it's status was neither accepted nor rejected, nor was it in 'limbo' (no status). It actually said "Updated on...." This was a new status to me!