I'm using bot for 2 years and not even once bought silk, i'm still boting. I used agbot and now sroking . I even bought gold 1000m , never played pvp, trade, or another job, i'm online and farm non-stop , so it's easy to see that my character is a boot .
My personal opinion is that GM's dont give a f.ck , the accounts banned belong to those players that made a mistake ( keylogger, password gived to a "friend" , bot instaled wrong or other situations ) or a system pics them following some criterias . Or maybe im lucky
My advice is to play legit if you don't want to risk , but without risks where's the fun ?