Misconception: These conventions are just for freaks and perverts.
Truth: Nothing could e further from the truth.  These conventions are mostly created by fans, for fans.  Hence the term "Fandom."  Man In Kilt has over a decade of convention security experience (both as a security officer and as a security coordinator), and can count the number of incidents he's handled on one hand.

Misconception: Conventions are dangerous
Truth: Well, let's be honest.  Just walking to school can be dangerous.
Any time you bring together a large cross-section of the population, statistics say that you will get a percentage of "undesirables."  This applies to conventions as well.  However, we can say, from experience, that safety problems are few and far between.