There was a recent Cracked.com article about crazy things people grew up thinking. A couple were:
"When I was a kid I thought cars were only good for about a year. My dad drove such cheap, junky cars that after a year he would drive straight to the junkyard and get a new one"
"My mom had an irrational fear of bacteria, so she would overcook every single meal. When I had my first medium rare steak in my late 20's I almost cried."
If the only pools someone had experienced was improperly managed chlorine pools, it isn't a terrible leap to assume that is how chlorine pools are. On the same note is the guy who thought all meat tasted terrible because all the meals he had ever eaten were burnt to a crisp. Given the posts I have seen I know a lot of members here love to cook. So if a guy were to say to them, "I hate meat, so dry and crunchy and just gross" they would be rushing to point out that everything he knew about meat was based on improper cooking and begging him to try a properly cooked steak. Well, pretty much every member here also loves their clear comfortable chlorine pool. So if someone says "I hate chlorine, makes me itch and my eyes sting and stinks terribly", we are quite keen to correct that misunderstanding. Unfortunately, proving it to someone is a bit more difficult than just sending them to a good steakhouse...