Bug in Polkadot Commission system.
The Validator Operator can set a commission to any percentage even 100% and if it is in the active set, changing the commission to 0% system will at that moment display 0% Commission.
That Validator operator could end up on the top of the Targets page and to everyone it will look like it is profitable unless the Nominator would go into the Validator Stats page to see the previous Commission.
That Validator Operator can repeat the process over and over.