I was going to post on the same thing. Lots of gel wrappers and bottles after Ribblehead and Hill Inn. We went for a walk around Ribblehead on Sunday and there wasn't any rubbish in evience which says a lot for the efficiency of the organisers. I handed my bottle to one of the spectators at Ribblehead who kindly agreed to bin it for me. Not hard to do really.
My wife was on the Sulber Nick water station and said that the majority of people were dropping off rubbish with her, so it must be a minority who need some sort of wake-up call.
You see an even worse problem on cyclosportives where a significant number of competitors think it Ok to drop gel wrappers and other rubbish on the road. I just don't understand how these people can think that it is acceptable.