If you avoid scam projects, you should little own research, if you want to check already listed projects in coinmarketcap that or scams or not then you need to check their rank and their exchanges some listed on Dex like pancakeswap or low-rank exchanges where trading volume increasing with the bot and pumping with a bot you should not invest low-rank project and check their social media and partnerships and also contract address should be verified and audited by companies. If the project is not listed in coinmarketcap then you need to invest in the project very carefully because most the projects pump their altcoin after that is gone, you should check their community and contract address are verified or not. so you can detect scam projects by your little research.