I've seen schools of fish on my fishfinder alot. Question is: what are they? Is it worth buying a camera that might show what they are, whether baitfish or crappie or some other species that school? All I knowi is that - they don'e bite anything I cast even when worked vertically.

From what I’ve read, you need pretty clear water to see what’s down there. I’d like to own one, but our water is filthy.

Water quality (clearness) is an issue, but if you can see a few few feet that may be all you need. Many times the fish in the area will out of curiosity approach the camera. Be prepared to drop the camera straight down on the cable, but there will be times you may need a pole to attach the camera to in order to reach some areas. I used the camera more when I had only 2-d sonar, but with side imaging and forward sonar, I don't use the camera as often. It still does have a place on my boat for those situations where there is a question on what is actually on the screen, but now the camera actually displays on fish finder screen so I only need to carry the camera which is very small and takes up very little space. Downside is you have to stop fishing and work with the camera. I cannot do both at the same time.

I'm hoping it will help discovering location patterns: deep water vs shallow, depth range, drops vs flats, bait fish followed by sport fish vs solitary fish, etc. It would not help in the pads seeing as that I'm not a pad dunker using a 7' rod.
Sideview would be preferred regardless. What unit do you have? I haven't owned a side imager in years and I'm looking to add one to the bow t.m. after removing the Helix 7 - keeping it on the dash attached to the stern transducer location already in place.

Even in stained water if you drop down the camera (aqua-view is what I recommend) on a school, whatever they are will usually come right up to the camera haha

I wanted an underwater camera too. I saw a couple of guys scuba diving in the boat house across from mine once. I guess someone dropped something and they were looking for it. The water was only about 7’ deep at the time. I asked them if they were seeing any big fish. They said they couldn’t see their hand in front of their face. So much for a camera in Eagle Mountain. I recently went to Broken Bow lake though and could see the bottom in 17’ of water and would loved to have had one then.