Translation:This tastes bad.
I was able to find a clear answer elsewhere. この is when you're distinguishing something specific in a group. It is always followed by a noun. If you have a handful of M and M's you would use この for "This M and M is red."
これ is for when you aren't using a specific noun in a sentence, or you are asking for something to be identified. "What is this?" "I need this."
When まずい is used describing food, usually it means how the food is like after eating it. So in that sense "tastes bad" carries a literal meaning to the original japanese sentence, whereas "is bad", or "awful" would be more commonly used in normal daily speech. It depends on what context you would want to translate to be more accurate.
I am leaving a gentle reminder for all the Japanese learners: It's considered rude in Japan to say "これはまずいです。” when you're expressing that the food tastes bad. Instead, you should say "これはちょっと......。” which means "This tastes a little......". It's left to the imagination after that.
I see. That's true too, but ”これはちょっと......。" is still more polite than ”これはまずいです。”. So, you should use the former if you want to express your opinion about the taste of the food.
It can be used to refer to a situation as well; it normally refers to a turn of events which causes trouble for you, as opposed to bad situations in general. So, rather than just something breaking, you'd tend to see まずい used if something broke and you were the one responsible for that something, or you need to use it in a hurry.
That really just depends on context. It would be rude to say this to the chef, but if it's something you made for yourself and didn't like how it turned out or if it's something weird you purchased and are trying out with a friend and you don't like it, or even if its not something meant to be eaten in the first place and you taste it it's not unreasonable or rude at all to go "Wow, this is gross"
By the way, 「やばい」 originally meant bad things as you say.
However, about 30 years ago, especially young people started using it in the opposite sense of "very good".
Currently it has both meanings, so we will judge in the context at that time.
・あれは めっちゃ やばい。/あれは めっちゃ うまい。/あれは すごく おいしい。
---That is very delicious.
---That guy is a dangerous guy./He's a wonderful person.
They both mean "this" and refer to something close to the speaker.
これ is a pronoun. It stands in for another noun.
"This tastes bad" これはまずいです
この is a pre-noun adjective and must be paired with another noun. (Note the linking particle の、it originated as a contraction of これの which is no longer used)
"This tea tastes bad" このお茶はまずいです