It's okay to not like things. I think it would be very hard to find someone in this world that likes absolutely everything they come across. To think that someone enjoys every single entry in all entertainment forms out there is mind-boggling. It's healthy to have tastes for things that you both like and dislike. Going just one way or the other 100% would make for a rather boring life!
There's a difference between disliking something and hating/bashing something though. There are people that dislike certain anime series', but they respect those that enjoy the program. Then there are people that hate an anime, and tell those that enjoy it that they're stupid and shouldn't be listened to. That's when things go too far. You may not like something, you can voice your reasons why in a calm and respectful way, but to bash someone for liking what you don't makes little to no sense.
With all the anime out there, it's not hard to find something you like. As you wade through all that content for the gems that you really enjoy, I'm sure you've hit upon one series that you just didn't like. Maybe it was the storyline and characters, or perhaps it was the art or dialog. For whatever reasons, you found an anime series that you just couldn't appreciate in any way.
I'd love to hear what that one series is, but only if you're willing to explain your reasoning! You can't say that you hate a specific show because it's stupid. There has to be a specific reason as to why you are so against a particular anime. If you're up to the task and ready to explain yourself, I'd like to hear what anime series you would recommend staying away from. Hopefully it's not too traumatizing to share the details!