VAC is worthless these days, in the competitive scene, you would see cheaters using a common cheat called CMD. Basically, one day a kid coded VAC proof cheats (isnt hard these days, their are thousands of them out now) and sold it to a couple people who gave it to their friends and so on and so on. My advice to you is go scrim, their are less cheaters in scrims than iceworld dm's and its quite a ball when youre fraggin with some drunk buddies at 3am. Unfortunately my css / steam is unistalled still but ill prolly get back into it some time.
PS: Leagues have been swamped with cheaters now a days. There was this one team (Learn to Play) that undoubtably cheated, every cevop player watched the demos and agreed that he was cheating. Now this team is cevop and i have no desire to get cheated out of my money. Although I must say ESEA has done a great job catching cheaters. It has a great anti cheat system but still isnt what all of us sourcers wish it was.