[You Dirty Rats]

So, "pairing" is a way to reduce the number of votes cast and permits Senators to hide which of the pair is on which side of an issue. That's about all it's good for

It's also useful if a Senator has a pressing engagement such as a meeting with a particularly hot lobbyist who's wishes to use her personal charms to influence a Senator. Since such lobbying can be "bipartisan", Senators will help each other out on this.

But enough about Senator Mikulski.

[Cboldt]

It's also useful if a Senator has a pressing engagement such as a meeting ...

I think it isn't useful to cover an absence. I think an absent Senator can't pair.