Code Reviews
Another thing it's safe to say that pair programming is not is a code review exercise; they have different goals. A code review should be conducted to discuss and improve existing code. Pair programming is about two people constructing some code de novo. If your pair programming is about one person writing code and one person saying they've done it wrong, you need to rethink your practices (or your partnership).
Mind you, that's true of code review when it's going badly, too. One problem with code reviews is that it's much easier to spot code that satisfies "I wouldn't have written it like that" than it is to spot code that satisfies "it should've been written to consider these things." This often gets in the way of getting useful information out of code reviews, because the reviewer gets frustrated with the tabs/spaces/variable names/other degenerate properties of the code.
It's problems like this that make me prefer...