This thread begs the question. Can you tell alot about a fisherman by his gear?
Depends what you're trying to determine.
You can probably tell less based on the brand and relative cost, and more based on the model. And a lot more if you get a look at his fly box. i.e. these things can tell you what kind of fishing a person likes to do.
i.e. if you see a cannon of a rod, combined with a fly box full of big streamers, maybe a big shot ring weighing down his vest, and spot some wire tippet, well this guy is into fishing big water for big fish. If he's got a Troutbum, a box full of midges, tricos, and the like, and 8x tippet, he's probably more the "finesse" type of fisherman.
You can also get a good idea when you see him cast. At least you can tell whether he's good or not. A beginner sticks out with totally improper mechanics, backcasts slapping the water even on short casts, etc. An intermediate has a nice, normal casting stroke, and it looks smooth and practiced. An advanced angler is doing lots of funky stuff, that to a beginner, may not look very impressive. Slack line casts for dry flies, tuck casts when nymphing, pile casts, etc.
But whether he's wearing Simms or Hodgeman waders, and carrying a Cortland vs. Sage vs. custom bamboo rod, probably not much. Maybe those Hodgeman's are backup waders. And most fisherman have multiple rods, covering the whole scale. And sometimes the Cortland will get picked up instead of the Sage for no better reason than he was in different mood that day.
If you see all the same brand, that might tell you something. But that something might be as simple as "he has a blog and that company sent him a bunch of free stuff."