Rome will be a ugly customer to you, if you don’t.

如果你不这样做， 罗马对你来说将是一个丑陋的客户。

To continue in fistic phraseology, he had a genius for coming up to the scratch, wherever and whatever it was, and proving himself an ugly customer.

继续用拳头的话来说，他有一个天才，无论在什么地方，无论什么地方，都能从头开始，并证明自己是一个丑陋的顾客。