1)2) 보이다 = looks '해 보다'는 ‘어떤 행동을 시험 삼아 함’이라는 뜻을 가지고 있어요. '먹어+보다' 먹는 행동을 시험 삼아 하다 좋은지 나쁜지 알려고 먹는 행동을 하다 '뛰어보다' 뛰는 행동을 시험 삼아 하다 '걸어보다' 걷는 행동을 시험 삼아 하다 try ~ing Have you tried this meal? It's good. 이 음식 먹어 봤어요? 좋아요. 3) We can say 맛이 없어 or 맛없어. 4)이 음식 보기에는 맛있어 보이는데, 먹어보니까 맛이 (전혀) 없어. =이 음식 보기에는 맛있어 보이는데, 먹어보니까 (전혀) 맛이 없어. =This meal looks delicious but it's not delicious (at all) after I've tried it.

Your question - 먹어보니까 = ??? "I've tried it" ??? #1. "보니까" in this sentence doean't mean "see", you would use "보니까" when someone tried(experienced) something himself. Your question 맛이 = "taste" and it's the subject of the sentence, right? - # 2. Yes, you are right. 없어 = "it isn't" - it isn't tasty #3. I think it would be easier if you think of the two words as a phrase meaning "it is not tasty." #4 보기에는 = seemingly = when someone judge by outward appearance 먹어보니까 = once you taste it, when you taste it, after you taste it #5 Personally, I use "맛없어"and "맛이 없어" both. Probably "맛이 없어" more often. #6. I think the reason why the translation have "at all" is the same reason in English, for the purpose of emphasizing. In that sense, the translation is wrong, so technically, it should have said "진짜 맛이 없어" which means "not tasty at all" It wasn't implied anywhere, nor the part of any word in the original sentence.

S 보기에는 Adj 보이는데, V 보니까 not Adj다. S looks Adj, but S isn't Adj after/when V. The girl looks healthy in the picture, but I could see she isn't when I met her in real. 그 여자애는 사진에서는(사진에서 보기에는) 건강해 보이는데, 내가 실제로 만나보니까 그렇지 않다는 것을 알게 됐어. You can say 맛없어 instead of 맛이 없어. I think they're about the same expression. I don't think you have to say "at all" there. It had to be "전혀 맛이 없어" if it had "at all".