Reviewing papers

Farbod once told me about a rule of thumb for reviewing papers. I think he attributed it to Prof. Jim Massey.

There are three conditions for rejecting a paper:
1. The results in the paper are wrong.
2. The results have been previously published.
3. The results are obvious or trivial.

I think that is a pretty good rule-book to go by, although I think I would add a fourth condition.
4. The paper is so poorly written that the reviewer, despite being knowledgeable in the area, is unable to make sense of the contributions.

It goes without saying that one should never undertake to review a paper in an unfamiliar field of research. It hurts the field by populating it with superfluous publications.