Can cards that are not affected by effects have their attacks negated?

Yes, cards that are not affected by effects can still have their attacks negated. The ability to negate an attack typically does not rely on whether a card is affected by effects, but rather on the specific mechanics of the game or card in question. For instance, if a card states that it can negate an attack, it generally applies regardless of the affected status of the attacking card. However, specific game rules and card interactions may vary, so it's essential to refer to the game’s rulebook for clarifications.