pay dirt
noun [ U ] US uk/ˈpeɪ ˌdɜːt/ us/ˈpeɪ ˌdɝːt/
（经搜索或付出努力后所作的）有利发现
something very valuable or very useful that is found after searching or effort
If a salesperson does not quickly hit pay dirt with a customer they will usually move straight on to someone else. 如果销售员发现某个顾客无利可图，通常便会转而寻找另外的顾客。