Red Flag was flying high.
After 3 years of flying most weekends, and with a number of different planes I'm always at least curious about how someone else has their stuff set up, so that's how I introduce myself. If I see some gross errors, I speak up and tell them that in MY experience it'll work better another way.
I've also helped guys that other "instructors" have helped by setting up their plane to the instructors experience level instead of the student's. Even trainers can be way too sensitive if set up for someone who likes to fly inverted passes. In one case I reduced all the throws to minimum and the student was actually able to land the plane himself with some gentle persuasion. I expect to see him back pushing a little each time till he needs a better plane.
We just suspended a flyer for being "unsafe". Two months suspension of priviledges (and revocation if he's caught flying during that time) and four months of probation. He had already crashed two planes in one day and smoked the third one in BEHIND the flight line without so much as an "Oh oh". 100 yard debris field and it was during our opening day with lots of people watching. So whenever a "new face" shows up at the field, a LOT of people are interested in looking at what he brings, how he checks his equipment, his range check, and his demeanor.
If its all new equipment, we ask if he's flown a long time, and actually scrutineer his plane. We offer to fix/repair/advise his equipment. If he's uncooperative, we check for his AMA card, and if he doesn't have one, we let him know that he's welcome to do anything he wants but fly. If he has one, everyone grounds their planes until we see how he flys.
In today's world, ANY breach of safety puts all of us at risk of either accident or losing fields. We fly on a country park field that we developed and built, and yes, everyone has the right to fly, but we made certain that the county gave us the power to enforce safety on anyone.