Most of the time when people say someone is hacking, its just a simple childish insult to try and claw back some respectability from the people on the server. 99% of the time, their simply saying it to try make their death look like a non-noob death, and still look 'pro'.

Half the time, I just ignore the calls of 'HAX! OMG liek tht dude isd hakng wel bd. Chk him plz', cause its just wasted time. If you have to ban someone for that, then ban the ass that cant take being killed.