They answer two different questions, and you usually need both.
"Has the token issuer (Tether / Circle) frozen this address?" A yes/no answer read straight from the token contract. But it tells you nothing about an address that will be frozen tomorrow.
"How likely is this address to cause trouble?" Sanctions, mixer exposure, tainted source of funds and behavioral patterns: the very reasons freezes happen. Run a full AML check →
Freeze events are read directly from on-chain AddedBlackList / RemovedBlackList logs, with continuous updates.
No. Many frozen wallets simply received tainted funds from a counterparty. That is exactly why screening before a transaction matters.
Freeze events are captured from token contracts as they happen, and Tether's pending freezes are picked up from multisig proposals, minutes before execution.
A clean blacklist result is necessary but not sufficient. Run a full AML risk check to also see sanctions, mixers and source of funds.