There are so many clever ways to code honeypots using obscure peculiarities of Solidity and/or Etherscan that there's little hope of being sure that it isn't a scam just by looking at the code and transaction history.

Fortunately, there are tools like Ganache, which you can run with `ganache-cli --fork` to reliably emulate locally what will happen when transactions are sent to mainnet. I would accept no substitute approach when dealing with suspect contracts.