2，Even really honest people are often made to feel guilty.

make, have, let 及感官性动词see, hear, notice, feel 用于主动语态，符合宾语不定式的to符号应该省略。但这种结构改成被动式时，不定式符号必须还原。
e.g. We heard someone come up the stairs.

e.g. Someone was heard to come up the stairs.

3, The hardened professional smuggler, on the other hand, is never troubled by such feelings, even if he has five hundred gold watches hidden in his suitcase.

(On the one hand...,) on the other hand

e.g. On the one hand we could stay and help you, but on the other hand it might be better if you went to help him instead.

hidden in his suitcase,过去分词短语作定语，修饰watches.

even if=even though新概念英语2

4, 'Have you anything to declare?' he asked, looking me in the eye.

look me in the eye: 两眼直盯盯的注视着我
同义词：look sb. in the face, stare sb. in the eye = look directly at sb.

e.g. Not one of the men dared look him in the eye.

5, The Officer went through the case with great care.

with great care----强调相当的仔细,全句相当于The Officer examined the case carefully.