I got my little Jalen this past Friday, and I tried to check him for signs of illness, but with the cloudy water, his clear body (he's a cellophane), and how much he was darting around, it was nearly impossible.
Once I had him in the tank and he settled down a bit, I noticed that his right gill was sticking out a little farther from his body than usual. I have lost two pet store bettas to acute gill inflammation before (I brought them home already sick), so I was immediately worried. However, I read somewhere once that the nasty water in pet stores can cause the gills to scar and appear inflamed, and his water was pretty filthy.
I would check for redness, but his gills are completely clear, and I can just barely see them when he flares. It doesn't help that he darts for cover like a little wimp. :P
He isn't showing any other signs of sickness. He has a healthy appetite, is very active, and even blew the world's smallest and most poorly-anchored bubble nest this morning.
I know that the best way to cure gill inflammation is to have frequent water changes, but if he's not actually sick I don't want to stress him out. I put a few drops of this betta 'revive' stuff (it's that blue antibacterial medicine) in his tank, but I didn't give him the full dose, just in case he was fine. I haven't changed his water yet, because I've had him for just over three days.
I would post pics, but I don't have a camera, and his gills probably wouldn't show up anyway.