anything to go by= if we take the example of Example of what older people often say: If today's teenagers are anything to go by, then heaven help the next generation

Do you mean “to be anything to go by”? The idiomatic phrase “if that’s anything to go by”, means that something is taken as an example, an indication or even as evidence or proof of something.

“If什么什么 is anything to go by, then。。。” 比如：If his bad attitude is anything to go by, then he is an awful person. "If 什么什么was any indication of 什么什么，then。。。“ 比如：If his bad attitude was any indication of his personality, then I don't want to date him.

to go by = to be judged by; to judge by If his attitude is anything to go by (= If his attitude is anything to be judged by) then we had better not employ him. If the weather's anything to go by (=if the weather's anything to judge by), then that's a great place for a holiday.

getting much clearer now, thanks guys~ ;)