I've worked on coke heavy sites, it's no fun , mood swings , their own mates selling it to them, even seen guys crying on the job totally fecked , I've had to share digs with guys who spunk all their money on coke ask to borrow a few quid on Monday, it's a sad lonely existence. I've declined work where I know I'll be the one doing piss tests etc to cover the others. I'm guilty of having too many beers now and again but it doesn't compare to the wreckage of cocaine... thankfully the more extreme sites are behind me , although it's going on ,on most large sites , I try and avoid those ....