They're located on the front row, even they arrive late. This is because the front row will always be reserved for these type of people (unintentionally). Usually these people wear glasses. They have the highest tendency to laugh at the speaker's jokes, even if it's not funny at all.
They're seated everywhere. It's easy to spot them- they're the one with the most head movement, up and down. This is because they tend to jot down everything the speaker says and written on the slide. They're like the reporter.
They always arrive late. They'll avoid sitting in the first and the last row. They'll find the blind spot to sleep, avoiding the hot zone like those seats next to the isle. They'll try to hide behind the head of the people seated in-front, staying away from the speaker's line of sight.
They're audible- whenever the speaker ask a question etc, their voice is the loudest. They will respond to every single question, being sarcastic at times, but when the speaker ask to raise hand (in order to answer), they'll shut up immediately. And not respond.
They're the ones who like to ask question- whenever there's an invitation for a question, they'll be the first one to raise hand. If they walk to the mic, they'll open their question with a lengthy statement- enough to qualify as a seminar on its own. Most of their questions can be considered as an irrelevant, silly question.
They usually occupy the back-row. Their attendance is only possible because of a mandatory order by their superiors. They tend to to take notes, but actually they're trying to sketch the speaker (without success). They'll also draw objects, including logo and emblem of leading brand-names.
They're seated on the back row. They're always looking at other attendees, observing each and everyone's behavior. They'll nod discreetly at times, as if they're agreeing with a point made in their mental note. Sometimes they also shake their head in disbelief, on how accurate a description they read about seminar attendees.
You're looking at another reader of the Black Zedd's Basic Literature. Kudos.