Most of the national forests I go to have a $2 per dog per night fee. I pay without complaint for my 2 dogs. I can enjoy hiking with my dogs, and that if worth the fee to me.
I wouldn't pay a dog fee at a campground that limits my dogs to the campsite and paved roads - if I wanted to just sit around the entire time, I'd stay home.
I stayed at an RV Park not too long ago. There was no mention of a dog fee when the group reservation was made, nor upon arrival. The first day, I brought my own baggies and the dogs to the dog run. There were no baggies in the dispensers and the garbage cans were completely filled with used baggies. I checked the small dog run and it was in the same condition. On the third day, the park management approached the group and stated there was a $3 per dog per day fee. Not once in the 3 days I was there did anyone empty the garbage cans in the runs (4 cans total). In the 3 days, one can had less than one layer of baggies added - that suggests that there was a good month's worth of poop in those 4 cans. I did not pay the pet fee. If they offer a dog run with baggies and disposal, then I will abide by that and I will pay for the added expense, but they have a responsibility to then maintain those facilities.