Who isn't cleaning up after their dog?

we are currently staying at Bridlington CC Great dog walk we have two dogs and take them on there every morning it is excellent and on several occasions have been surprised and disappointed to see dog waste not picked up and placed in the dog bin which is present at the beginning of the dog walk.  If you are reading this and are guilty of not picking up at any club site.  Why?? as it gives all dog owners a bad reputation.