There are many scam tokens on UNISWAP that aren't known to the world and not available on coinmarketcap and coingecko, you can detect  them by their smart contract address, but they mostly have same name with a real working project, assuming a well known token is named Apple, scammers will name their token Apple too but the only difference will be the smart contract address, this is why one must check smart contract address of the original token they want to buy on Uniswap before diving in