I just ripped a guy a new ass yesterday for that same thing. First off, he wasn't doing jack shit but going through motions, then he was using chalk, then he was taking forever in between sets. Finally as I walked over to him, he started to walk away, I asked if he was done there, and he said yes. So I snapped and said, well why in the fuck don't you clean up after yourself?!? Put your fucking baby weights away and clean up your chalk mess!! If I get that stupid chalk on my clothes, I'm coming to you for reimbursement!" I thought he was going to cry. I thought a couple of the trainers were going to cry from laughing so hard.