I usually go the most common route of explaining that they are no more dangerous than a moody Chihuahua - and usually less chance of getting bit, they don't bark or shed hair everywhere, they go through way less food, and they won't feel neglected if you don't have time to spend time petting and playing with them. Most people end up with the "well that coll I guess, just not my cup of tea" sort of response.
I will say one of my co-workers is a snake murderer who kills any snake she sees and after the third time of asking her not to talk about it around me (she brings it up even if I am talking to someone else - several of us have reptiles so it is a common topic)...
and one day I lost my temper a bit and said that it was just as hurtful for her to tell me I should kill my pet with a shovel as it would be if I pointed at her Yorkie and said I routinely run them over with my car and I think that should happen to her dog too. Of course she got super upset that I said such a thing about her beloved dog, but at least she stopped talking about beheading snakes around me.
I hate to make someone feel bad; but no one should take the life of any creature just 'because I don't like them' or they think the animal is gross. And if they are going to constantly talk about it to people who have asked them to stop, then they can just get their feelings hurt - because I won't put up with it. *End Rant