In reply to Rigid Raider:
Coed Llandegla was like that the last time I visited. The amount of litter left by mountain bikers was very surprising. Pop bottles, sweet wrappers, old inner tubes etc.
I think the worst cycle route for litter I have ever been on was the section of the Cardiff - Anglesey route, Lon las cymru, between Cardiff and Merthyr Tydfil. The entire length of the section was absolutely littered with filth. Not just bottles, cans, wrappers and dog sh1t, but old sofas, car tyres, old pallets, you name it. The amount of litter was disgraceful on what is a national cycle route. It is as if the people living there had no pride in their area whatsoever. Rivers, footpaths and cycleways all similarly littered with crap. Once out of the South Wales valleys the litter disappeared, so I can only assume it's the local people who think it's OK to live in what looks like a massive landfill site.
Conversely, I cycled across Switzerland and saw virtually no litter in over 250 miles. Everything was clean and tidy. The same in Scandinavia. It must be down to education and taking pride in an area; something which seems lacking in the UK.
A small minority of people in the UK just seem to like to live surrounded by crap. Perhaps they don't even notice it or are aware of the problem it creates.