APB will always have that problem, especially with a lot of newer players who haven't been around for more than a year, they just don't have the experience or time to understand all the nuances of the mechanics in the game. Players see someone "flick" shot and they cry 180 snap, aimbot, players get spotted by the mod, and they cry wallhacks, players get outaimed by someone who has more talent then them, and most likely has played the game since 2009, and they scream, he must be cheating. Players get used to playing low skill / casual players, and they are opposed against a team of competitive experience players of a higher skill level, and bam, once again, they must be cheating. The size of the game causes a lot of players to develop a massive ego, in a game so small, everyone pretty much knows everyone, or at the least has seen them around, or played them once. Even some of the players who have been around since 2009 have absolutely zero self awareness and have never even taken the time to even think that some players are just better than them, in their minds, they are the best, and everyone else must be cheating.
This game really does not have a very big cheating problem, I cant even remember the last time I felt cheated in this game. What everyone needs to do is sit down, have a glass of water, take a deep breath and get over it. On a final note, if you really think someone is cheating, shut up about it, report it if you want, and just play the mission. Win or lose, it doesn't matter, One of the most important things I ever learned was that you will never improve in anything you do in life if you don't constantly challenge yourself. That works in every aspect of your life, YES, even in a video game, I'm not going to stand on a pillar and call myself the greatest player to ever touch the game and stroke my own ego, but I will say that I definitely got better from playing some of the blatant cheaters in this game, and learning how to fight top tier players. Going AFK and logging out against better players, or "Cheaters" only hurts your overall skill level in the long run. Every time I get the chance to play good players, I take full advantage of it, because lets face it, it doesn't happen every day, and every chance is a learning opportunity.
TL:DR - Take it with a grain of salt, use the challenge as an opportunity to get better.