I hate when people complain about "cheap" tactics. If it's in the game, some people are gonna use it. And so what if they do?
If they keep killing you using a cheap tactic, why not give them the taste of their own medicine? E.g. if they keep killing you with the noobtube, why not get one of your own and get revenge? Oh, because you are using tactics which are "skillful" which entitles you to some sort of high ground.
I ditched this sort of attitude very quickly when playing multiplayer games. It's just going to get you mad and raging, rather then enjoying the game. I play as a sniper in most games, but if I get noobtubed I just laugh most of the time. I'm pretty good with a sniper, so in a game with one-shot kills like CoD4 I'd say sniping is pretty cheap. You just point at stuff which you want dead, and it dies. Try going around a large map like Overgrown with just a noobtube and see how well you do. Maybe these people do have skill. What people use is their personal preference. I don't think a player is any more nooby for using a noobtube than for using a sniper, or a shotgun etc.
I agree that hacking is very annoying, but I wouldn't really call that a tactic.