vac scans multiple things.
some ppl even think (i dont know if its true or not) that vac runs even if your game is off but not when steam is off.
if vac is scanning and "sees" the cheat client, and they know which client isnt allowed, than your name is on the blacklist.
after an x amout of time (1day - 1 month) everyone on that "list" gets banned at the same time.
with this way, they can collect more hackers and ban them all together, why? just bcs of this situation right now.
ppl got banned, chod disabled the cheat instantly.
if they wouldnt ban in waves, the first couple ppl who get vaced report it and save others account by telling it asap.
volvo isnt stupid
anything else i can try to explain?
PS the cheat is disabled so noone, who isnt active on the forums, uses the cheat while its detected.