I hear it a lot, but after having 1 valor 100 and 2 valor 80s, I have seen possibly 1 hacker. There are many glitches, and a few exploits, some that I confused for hacks when I didn't know the game as well. I hear it is becoming more common in lowbies with f2p, but I honestly don't see it on my lowbies either. I have, on the other hand, been called a hacker about 20 times in the last month... I have never cheated, I just know all of the game mechanics really well and new players just don't understand the vast majority of them.
100% this. I have only seen 1 guy ever using a hack of any kind, and he admitted it later on to me. I play sage in pvp and its amazing how often I'm called a hacker or cheater. In the outlaws den yesterday I was just killing time waiting for ques. A Mara jumped me and got bubble bursted, he broke cc, and I lifted him and healed to full. I then ran off a bit and started unloading on him. When he got close I used knock back on him when he had full resolve (this doesn't knock back with full white bar, but the root still happens) and I killed him in that time. He came back and in /say he kept saying "nice hacks noob. You have to use cheats to beat me. Reported. Scrub." People like that are 99% of the "omg hax" problem.