Yes, In Swedish, things taste, smell, and sound adverb, whereas for some reason they use adjectives in English.
Where I'm from, what they call lox (usually a bagel and lox) is a word instead called gravlax in Swedish.
Yes, "illa" is often used with senses:
det luktar illa, han ser illa, hon hör illa etc.
Norwegian and Swedish has several words in common, but mean different things:
Swedish: (adj.) funny
Norwegian: (adj.) calm
Swedish: (v.) stealing
Norwegian: (n.) rope
Swedish: (v.) sex
Norwegian: (n.) company
bärs/bæsj (similar pronunciation)
Swedish: (n.) beer
Norwegian: (n.) poop
When I typed it into Google Translate, fount of all accuracy, I got: "denna lax smakar fult". [Denna is another way of saying this.] The adjective ful in Swedish is often used for ugly, but presumably 'foul' is a closer translation. Because of how synonyms work, I'm sure you could translate the sentence as 'foul' in this case, but 'fult' is apparently a better direct translation.
Fun fact: In (UK) English we are more likely to use the adjective 'foul' for a taste, smell, mood, or personality than for appearance (unless something looks like it will taste/smell foul etc).
Edit: I was a bit wrong- see comment below.
fult in the meaning of "foul" is generally for e.g. "foul play" and similar. It can not be used for tasting foul in any way.