What's the best way to beat a lag switcher?

A lag switch is a mechanism that allows inserting delays into the flow of traffic on a network. When used during a video game, it has the effect of having the character appear frozen in the game while the cheating player can continue to play locally as normal and gain advantage over his opponents.

In Black Ops, there are tons of lag switchers. You can tell when you're playing a game and there are 5 host migrations in a 10 minute round. That, and just general game play.

Now, my question is how can us fair gamers beat these cheaters? Are there any anti-lag-switch type devices? Or any particular style of game play that is lag-switch resistant?

There isn't really a way of stopping lag switchers.

Lets put it this way - whatever you do, for them you are simply standing still on the screen unable to react to anything. The only way to stop them is to not be in their way/to hide.