Having spent some time on both sides of the lense, You have to accept advertising pics as what they actually are: specifically, "carefully choreographed artistic renderings designed to elicit specific emotional responses." It doesn't make much different what they are advertising, could be gear, or could be training, or could be just a pic to hype an article in the mag. It's there to sell you on something ... whether it's real (gear or training) or a fantasy wish projection (like a dive trip destination you've never been to) Each pic is carefully composed to tweak the emotions of it's target demographic segment. Most diving pics seek to elicit; free spirit, carefree, this is so easy, that looks like fun, there's nothing to it, kinds of feelings. To that extent, expect sweeping lines, like a dangling console or octo on it's hose, look for lots of loose flowing hair on female divers. (in the real world, I don't know any women that don't keep hair tied back) Don't expect anything that tends to make a pic look too busy. Note the conspicuous absence (to experienced diver's eyes) of bubbles, especially if they might be between the viewer's eye and the subject's face. Foreground bubbles are busy and distracting. Look for positions that might seem confortable out of water to a non/new diver. Perfect horizontal trim looks difficult and uncomfortable to new/non divers ... They'll get the "I'm not too keen on that" (whatever is being advertised) emotion. They see people kneeling on the sand in a group (for whatever reason) and they feel the warm fuzzys of "I can do that, that's easy" show me more I'm interested emotion.
Whether you're trying to sell people expensive gear or sell them on the idea that learning to dive might be easy, fun, and within their ability, pictures say thousands of words and elicit emotions not reachable with verbal limitations. For each pic you see, there were likely hundreds of rejects that just didn't "get the right feeling conveyed"
When it comes to pictures in advertising, it's a lot more of "what we don't see, than what we do see", that counts the most.
Pictures in dive publications are a lot like pretty fishies on a reef dive, nice to look at, but if you waste time analysing them, it ruins the dive.
Darlene