"You have bad taste" is this context is a slang which means you like something that most people would think is ugly or dislike. For example, "People who likes the Tesla Cybertruck has bad taste." On the other hand, the idiom, "In bad taste" means an inappropriate or offensive action.

Bas taste generally means "to have poor knowledge, little idea, lack of judgment" about something. however, if you are using this in the context of food, as in, if someone says he had a bad tase to that food, it would mean that he probably won't try that food in the future and he does not like that food. I hope this helps. Good luck!

It means that you always make the wrong choice or choose the wrong one. It is usually used to talk about relationships like "I have bad taste in men" this means that the person always has bad relationships because the men they choose are not good.