"This idea fascinates me," says David Hurn; "the idea that a few seconds of watching a photographer in action can tell you his/her status in the medium. And it's true. If you watch a photographer of merit working an event he/she does not look like an amateur…”
--Jay, Bill; Hurn, David (1997-10-01). On Being a Photographer
Pros don't spot pros due to gear, they spot them due to work habits when shooting.
I was covering a workshop for college students in Nashville, TN one year, when I walked into a theater and everyone in the class was down front and the teachers were sitting on the edge of the stage. After shooting a few photos around the front I went up on stage up behind the teachers to get a good shot of the students listening to the instructors.
Just as I did that the entire class broke up laughing. Talk about an awkward moment for me, but quickly Anacleto Rapping, one of the teachers, let me in on the laughter. He had noticed I was covering the meeting and was teaching these photography students that if they just waited at some point Stanley would come up on stage and make some photos.
My walking on stage to make photos in that situation would be very typical for a photographer doing reportage on the event.
When I teach students I am teaching basically actions that if they do will give certain results. Put a light here and the subject here and you will get a certain look.
What is key to understand is while the results will vary from each photographer, most all successful photographers will fully explore a subject. They will move around the object and due to some physical limitations will most likely avoid similar photos.
Just how a photographer holds the camera is often a giveaway that they know what they are doing.
Would a professional photographer acknowledge that you are a fellow pro or a rank amateur just by watching you work?
Most all professionals will not conclude that because of the way you shoot you are a great photographer, what they are concluding is that from your actions alone they would approach it similarly.
I can spot a pro even when they are using a point and shoot. Can you?