As others in this thread already mentioned here in this thread, the biggest and most reputable DEX for the Ethereum Blockchain is Uniswap, for the binance smart chain it's pancakeswap and for polygon it's quickswap. You can never be 100% sure that such decentralized exchanges will always work or will never do a rugpull or something like that but with this 3 Dexes i think the chances for a bad experience are the slimmest.
That coins are launching on one of these swaps does not mean though that those coins are automatically promising and not a scam because everyone can list his own token on any Dex without being audited or something like that. So you still need to do your research on those tokens even if they list on the big Dexes.