Another popular scam technique is called an "initial coin offering (ICO)." A potentially legitimate investment opportunity, ICOs are essentially a way for startup cryptocurrency companies to raise money from future users: In return for sending active cryptocurrencies like bitcoin and ethereum, customers are promised a discount on new cryptocoin.
Having an ICO doesn't make the coin/token a scam, most big market cap coins/tokens have ICO on their end but look where they are right now. IMO, the most successful one is Ethereum
https://icodrops.com/ethereum/ and that's almost x2000 gains to those hodlers of ETH this time around. But we can say that almost 90% of those that conducting an ICO will turn out to be a scam.
Not all ICO but you can easily say if the project is scam under the ICO program and this is why scammers are also trying to do a project under IEO and DeFi because this is the new trend now. We have to understand how the scammer works and take our necessary precaution before investing into a project, if you are doubt with the project you can easily ask here if the project is legit or not, don't rush things to invest on new project whether its ICO, IEO, DEFI you have to analyze it.