As a frequent visitor to the West Arvada Dog Park for the last 3 years I have noticed that we have few of the problems as noted in other parks around the Denver Metro Area.
This is probably due to the culture of the dog park. Most of us have been visitors for quite a while and many friendships have developed both human and canine. New visitors are usually greeted by a regular with just some friendly conversations about their dog.
Often we are so busy talking we don't see our dog relieve itself. So we have a secret code. When another visitor sees our dog do this, they just say "Hey (insert name) your dog just pooped." Upon receipt of this secret code the owner then cleans it up. When we don't see our dog poop or just out of habit we will usually pick up another dog's waste product, kind of paying it forward (or backward if you will). We will often just offer the other person a bag to clean up the poop. This subtle hint usually works and no one takes offense.
This type of community culture can only develop if the participants are willing to do so. Ours is not the only dog park with this type of culture, and there is no reason the other parks cannot develop one. I would encourage regular visitors of any dog park to help create this caring attitude. It is not hard to do, and is very rewarding.