If you spot a
dodgy thread which is of
no interest to most people
...mark it as a 1 rating. Then your fellow PPRuNers can avoid them, thus saving a great deal of time.
Conversely, if you spot an
interesting thread, grade it 5 and everyone can visit those first, also saving time.
Grade 2 to 4 for all points in between.
(P.S. It wasn't me either)