When you work at a pet store and get super protective over all the bettas...
I honestly lurk around the section when I see people near them. If they sound like really bad betta owners (example, I hear them saying "this fish would look really cool with my gold fish" or "Hey, you have that little bowl at home right, that should work") I jump in and either REALLY emphasis the proper care of bettas, or I exaggerate the basic care of bettas and make the customer not want one anymore xD Most people don't like hearing that they will have to clean their little bowls at least once or twice a week.
If the customer is willing to listen and honestly try to give the betta a good home, I am more than happy to discuss proper care for a betta with them. However, if I know for a fact that harm will come to the betta, I will refuse to sell it them. One customer was determined to put two males together in the same bowl. She already owned the one, I flat out refused to sell her another.
I'm very protective over all the bettas in the store. I care for them and take care of them like they were my own. Often I end up buying my favourites or giving them as gifts to my friends who love bettas as much as I do xD