Fairly, it's OK: cũng + adjective

You know cũng as "also". With an adjective and nothing to point back to, it means "fairly" or "OK": a lukewarm verdict. Asked Phim đó hay không? (Was that film good?), you answer Cũng hay for "It was alright". It's polite but cool. Khá hay (quite good) is real praise, and hay lắm is enthusiastic.

Cũng được is the everyday "it's alright" or "it'll do": Quán này cũng được. It also accepts a suggestion without much excitement: Đi bộ hả? Cũng được. Walk? Fine by me. For "so-so", people say cũng tạm: Dạo này công việc cũng tạm.

How do you tell "fairly" from "also"? If someone else has just been mentioned, it's "also": Anh mệt, em cũng mệt. You're tired, and so am I. If it's a verdict on something, with nobody to compare, it's "fairly".

So take care with praise. To your host, cũng ngon sounds like "it's OK"; say ngon quá or ngon lắm instead.