Such parts are often considered to be thankless, unrewarding.

这种角色通常被认为是吃力不讨好的。

Why is it so unrewarding for politicians to bash the rich in America?

为什么美国政客都不愿意对富人进行打击呢？

Low interest rates have made bonds and bank deposits unrewarding too.

同时低利率已经让债券和银行存款变得无利可图。

You find the process of reaching the goal boring, frustrating, or unrewarding.

你发现实现目标的过程乏味不堪、令人沮丧甚至根本不值得。

Lectures often seem very formal and empty things; recitations generally prove very dull and unrewarding.

课堂讲授常常显得一本正经而空洞无物；背诵往往非常枯燥而收效甚微。