What do you think causes the crackle and clicks we hear?

In my case, most of the records that I play are new re-issues. I use an anti-static fiber brush and zerostat, but these are only marginally effective. The VPI vacuum doesn't get much work unless I've picked up used records from the local bookstore.
I have noticed that the clicks and crackles are mainly on my TW Acustic especially when I was using the copper mat on it, the issue is lessened a great deal since I've gone with a different mat on this table but still present. The copper mat doesn't seem to be problematic on the two Garrards though. My guess is the TW setup is just more prone to static for some reason. It could also be a tonearm/cartridge resonant issue, but I haven't narrowed it down yet.
I don't think phono overload is the case here since the noises were present with a Pass Labs, a Jasmine, and a King/Cello phono stage.  

@johnss 
Last night I gave my noisy crackle 180 gram a really good cleaning, and whaddya know the crackling went away! I also noticed most of the static was removed from the record which was what I thought causes the crackling. I'll test out more records in the coming days.

use your favorite cleaning solution, apply it to LP. spread evenly across the LP surface. Let is sit for 10-15 min then vacuum off.

@johnss   That sounds simple enough, I'll give a try shot.
 

Will someone kindly provide a link for the  "Atmasphere phono overload" thread, I'm unable to find the relating thread.
Many thanks, Anthony