Came here to write the same. I'm real happy when someone runs ahead of my limit orders and provides me liquidity/execution. If I wanted to pay less, I would have set the limit lower.
You can set a slippage tolerance when you make an order on a decentralized exchange. It's basically the same as a limit order priced to market, where you effectively set the "most you're willing to buy for" / "least you're willing to sell for" and occasionally get better rates.
With a DEX your transaction might just not execute at all some of the time of creating the transaction, so you might burn a transaction, and there's no orderbook for the order to sit in til later.
With a DEX your transaction might just not execute at all some of the time of creating the transaction, so you might burn a transaction, and there's no orderbook for the order to sit in til later.