Too often one or two dogs will come barrelling down the trail and they bother other hikers they encounter. Plus they go after the wildlife.
I am not opposed to dogs on the trail and I realize that leashes don't always work in the more rugged areas. But don't let your dogs just run 100 yards ahead. Keep them near or leave them home. Most people do well at this, but some just allow their dogs to do whatever and they get hyper and aggressive. I get why--it is stimulus overload for them and they are in their element.