yes, the water bowl is dirty. But the hen doesn't actually look bad to me. And the fact that she is jumpy means what?? Nothing at all.
Roosters with scars kept separately? Nothing in itself
Roosters with long spurs? Nothing either
Did you know that many "fighters" actually remove the natural spurs and attach fake ones?
Locked in a stall? again, means nothing
Being yelled at for sneaking in? Means even less. The birds look like game breeds, so it is possible that they are separated because the roosters do tend to fight. They could be locked in a stall because of people like you actually. People who see them and want to go look at the birds. Some birds, esp roosters, are people aggressive. They could lose their business in a lawsuit.
Also, did you know that breeding, owning and selling game birds is completely legal?
Rumors that they fight birds? There is a rumor in my neighborhood that I own a coyote. (He is a sable German Shepherd and the woman is an idiot) YOU are starting a rumor that they are fighting birds. Maybe other people have done the same and that is why there are such rumors?
If they ARE fighting birds, what do you think leaving a note is going to do?
Do you actually think they are going to let someone they don't know, a kid at that, just walk up and start talking about fighting and say "sure, come over and we'll fight some birds!"? And if they AREN'T doing anything, then you have yourself on tape trying to solicit illegal activities.
I would report your suspicions to the authorities. And don't be surprised if it looks like nothing is being done. To arrest someone for this, there needs to be solid solid proof. Something besides birds in cages. Also, they prefer to catch the whole gang, so will try to get inside and witness an actual fight. That way, they can arrest all of the people involved, not just one player.