If you made a mistake and sent funds to a validator rather than voting for them, then you need to contact that validator and ask them to send your funds back. 

Polkadot validators are likely to return your funds because the Polkadot ecosystem is designed to incentivize good behavior. This tends to result in more votes and trust from the community and therefore more influence and financial rewards. The opposite is true for bad behavior. 

However, be aware that since it is a decentralized system, not all validators have verified their identity with a registrar on Polkadot. Registered validators are marked by a green icon (with a checkmark or chain) next to their name in the Staking section. Clicking on the name of these validators gives a pop-up with their information, including Twitter address, email, or website. Validators with a grey icon have set an on-chain identity but their information hasn't been verified by a registrar. Of course, it is reasonable to expect the information is correct.

Be sure to share your experience in the Polkadot community on Element, Discord or Twitter, so the whole community can also learn which validators are the most trustworthy.