We know some ICO and IEO are scam with lower interesting by investor, always checks how many investor have buy and invest their money at some cryptocurrency project.
However, this is not always true. There are also big ICOs way back then that turned out to be a scammed in the end, a lot of investors bought that coins believing that it would be a good investment, but sadly, it was just a disappointment for both investors and bounty hunters, that is why identifying cryptocurrency scams would be a headache, the only thing that we could do is just trial and error. But in my experience, the most easiest way to spot if a certain ICO is just a scam is if they can't provide solid information about their ICO, they don't have any website or their whitepaper is just copy pasted on other ICOs.
Of course, scammers are very intelligent, smart and very adoptive to the things happening to the market. Scammers know the psychology of the people who are looking for opportunities to make money so they can be appealing to greed that even the very professionals and experts can be fooled. The only best way to know a scam is when it has already turned out to be...which is of course already very late otherwise one should just shy away from getting involved with this industry.