BOUNDARIES: Not just lines on a map.
Boundaries, and the breaching of, is a touchy yet very necessary red flag to bring forward.
Despite fandom being a welcoming and safe environment, unfortunately some ugly incidents at conventions do occur - either by attendees or those seeking to cause disruption.
No means NO!
It's an unfortunate reality there are those who don't understand personal space or somehow feel entitled to your time and efforts. Pushing boundaries also takes the form of (presumably) grown adults nagging (the stuff children do) as a tactic to achieve whatever it is they're after.
Any person, organization, or event exhibiting that or not taking reasonable actions to address that are a red flag requiring scrutiny.
Cosplay Is Not Consent.
If you see something, say something - call for convention staff, or if feeling safe to do so get involved.
Don't be afraid to call 911 if there's an unsafe situation.
Do note that in Canada, stalking is a form of criminal harassment, and is an indictable criminal offense.
Pushing boundaries also takes the form of engaging in acts that can be considered degrading, harassing, exploitive, and even potentially dangerous.
In July 2000, someone brought along a radio scanner to intercept communications and wore clothing to intentionally impersonate (this wasn't cosplay) official convention staff and interfered with a medical situation. That person was removed from the event.
In Spring 2006, someone coerced another congoer to go find and capture below the belt photos of unsuspecting young women. Unknown what the end result was to resolve that incident on site, but affected attendees were advised.
In July 2007, a 'comedy' show crew arrived at a convention with media credentials claiming to be filming a documentary - they soon began to harass or otherwise demean and disrupt the event and were promptly removed. They were previously banned from another prior event because of incidents including encouraging people to engage in violence (including a submission choke lock), absolutely dangerous and unacceptable.
In early 2019 the person in charge of a convention held a meeting and told people not to do anything in case of any complaints of harassment, claiming that [they] were likely going to see women faking harassment in order to "attack the convention" and "take it down" ...thankfully that person will never run a convention ever again, such a lousy legacy.
We're all in this together, and we all have the ability and responsibility to encourage and sustain a safer community.