If you don't have anything nice to say...
I'd like you to imagine a scenario. Think about the animal you love most: cats, dogs, whatever. Suppose it's cats, for the sake of argument, but if you don't like cats, just replace "cats" with some other animal you have adoration for. It's the same principle. Suppose you mention that you love cats to a friend, perhaps mentioning your pet cat, or that you'd like to adopt a cat of your own one day.
Now, suppose that friend responds by telling you how much they despise cats, and that they regularly butcher cats because they gross them out, or that they have an attack dog just so that it can kill any cat that comes near them. Perhaps this person says they don't have a problem with cats existing; they just want them to be out of the city and stay "where they belong", in the Sahara Desert.
I would imagine such a person would cause you to be very alarmed, and you would probably consider that person to be not just distasteful and rude, but murderous and insane. Yet this is exactly the same sort of response I encounter almost any time I bring up my affinity for my favorite group of animals: spiders.
It's almost like a law. Any time I bring up my affinity for spiders, some crazed arachnophobe immediately butts in with how they kill them if they see them, how awesome it is that their cat eats spiders, how they creep them out. Often they will springboard onto an excuse, which goes something like this: "I don't have a problem with spiders when they're outside, but I can't have them inside/in my sight!" Of course these arachnophobes are completely oblivious to the fact that the spiders they find indoors have always been indoors, evolved to be indoors, and would perish outside the same way your average domestic cat would perish in the Sahara Desert.
I understand that arachnophobia is not a choice. It's terrible that some of us have evolved to fear one of our best friends, the spider, which kills pests for us (not unlike how cats kill mice, coincidentally) and is at the same time completely harmless to us. So I'm not angry at you for being an arachnophobe. I'm not even angry at you for being ignorant of the fact that spiders found in your home only belong inside your home, that putting them outside is dooming them to peril.
But to tell me how much you hate spiders, how gleefully you kill them, and how you won't allow them to exist in your house, when I was just saying how much I love spiders, is not appropriate. This comes back to an old saying: if you don't have anything nice to say, don't say anything at all. Think back to the cat example above. Replace cats with another animal you adore if you need to. How would you feel?