It really depends on what you are trading. For example the prototype of a "dumb" insider trade is getting OTM call options when you know a company is getting a

It really depends on what you are trading. For example the prototype of a "dumb" insider trade is getting OTM call options when you know a company is getting a blowout quarter. Large amounts of OTM options trading in a stock that rarely sees much options activity is quite noticeable. When the authorities notice those, they can (and do) find out who got into that position simply by calling all the registered brokers and asking them who did it. (With a court order if need be, because suspicious options activity just before large jumps in stock price is reasonable suspicion of insider trading)