Idiomatic Translation: Guilty Pleasure
How about 恶趣味? Literally &quot;an evil interest&quot;.
For your example,

For the renowned sushi chef, eating fish sticks drowned in tartar sauce was a guilty pleasure.
对于一位有名望的寿司师傅，吃着配上塔塔酱的鱼柳条是种恶趣味。

Some other interesting translations include:

罪快乐. It takes the pronunciation of 最快乐 (happiest) to imply that it's the happiest, yet a &quot;crime&quot;.
罪乐感. It derives from 罪恶感 (guilt) to imply that it's a guilt which makes one &quot;happy&quot;.