As an avid enduro motorcycle racer, 4-wheeler, and member of several Off-Highway Vehicle organizations, I know that the VAST majority of OHV users are great people who not only respect the wilderness and private property, but we also have work parties to maintain trails. In fact, we motorized users do while the preppie mountain bikers don't! They trash streams and trails and never participate in trail maintenance.
That said, anyone who decides to f*** up someone elses property, including public property, needs smashmouthed and hard. Judges should be, and usually are, willing to send the idiots to fix their mess and then "donate" a few hundred additional hours to the work parties. We always seem to have a dips*** or two in every work party. In fact, we petition the judges to give them to us. We get to teach them a bit about respecting the land and each other. We do it "nicely", but they get the point. Some even come to be respectable members. We police our own.
It's the cretins who go off roading on tempting private property who have ruined the group reputation.