The best way to find the people using an autoblock program (*cough*crymoar*cough*) is when 4-5 people are swinging at same time at them and the blocks switch to each strike within 1/100th of a second and blocks each and everyone. There is no human being on the face of the world that can do that with greater than 0 ping because they dont register in that time.
And yes there is without a doubt some people that do use that hack. You play long enough you see the peasant with a club that is without a doubt afk and has the block switch automatically as soon as you start to swing, just like there were some people post-patch who had programs that would make their character randomly walk across the map and reload a xbow after shooting in a random direction (get xp/gold), then would eventually get stuck walking into wall before randomly going off bridge lol. Recently I saw on siege server some guy closing the gate and holding the ctrl key to do so facing half away from the attackers yet didnt move even 1 pixel yet blocked several varied atatcks from different angles and closed the gate iin the process.