I have sometimes wondered if the bees have some sort of negative reaction to chlorine. I try to swim three or four times a week and it gets to the stage where I can smell the chlorine when I shower at home even when I've already showered at the pool. Spend enough time swimming in it and it just doesn't seem to go away.
You get to questioning all sorts of things given time though. I had an SBI inspecting a colony a few years back and they were good as gold for her. She asked if I could assist and as soon as I stepped forward they were all over me. I was stung several times within a few seconds and walked away whilst she carried on quite happily working her way through the hive. Perhaps I just trigger some species memory of what a big scary bear coming to steal honey looks like
(This may not be utterly implausible. Many of my daughter's friends' initial description on meeting me is "scary". I'm not sure why. I'm quite a laid back person. It's entirely possible that I look like someone who could rip your arm off and beat you to death with the soggy end though.)
James