A couple weeks ago I played a game of Anniversary Classic BTB Slayer on the Hang 'Em High remake. Game started off fine, then got extremely laggy very suddenly. All the connection meters on the scoreboard went red. I caught up with one of the top players on the other team who was magnum-sniping my team while they were spawning, got behind him, was about to assassinate him but he quickly turned around to face me so I ended up just punching him in the face. Whatever. His shields are all the way down, he doesn't get a chance to hit me back, I start unloading my magnum into his face figuring I'll get the kill any second but out of nowhere: lag hits. Screen freezes for a split second so I don't even get to see how, but I come back dead with no kill. We're losing.
Keep in mind that a friend of mine who I was partied up with, who has a great connection, was in the same game as me and ended up walking away from the controller because he was getting frustrated with the lag. A couple minutes after he walks away everybody's connection meter goes green, I start kicking some ass, but the other team's still maintaining about a 20 point lead. Games about 3/4 of the way through when half of the other team quits.
I start thinking "Oh yeah, comeback time! We can totally do this, these guys are terrible!" Bam, lag hits; scoreboard shows all red connections. Convenient. Needless to say: we lost. One guy on the opposite team had forty-something kills if I remember right, and the guy who somehow managed to kill me with no shields and with me unloading a magnum into his face had 27 kills by the end. Nobody else did nearly as good, not even on their team.
I managed to make it out with a positive K/D but obviously I was annoyed. I don't think it's as simple as a "lag switch" but I do think if you get host and know what you're doing, you can influence the game in a severely unfair way.