Remus pushed open the door and cleared his throat.
"Hello," he said, shutting the door behind him carefully. "I'm here for the potion, as I'm sure you surmised."
He peered towards the cauldron Snape was tending. It looked foul and Remus suppressed the reaction to gag a little. The steam rising from the boiling liquid smelled a bit like wet dog, even with a congested nose. He didn't really want to know what it smelled like when all his senses were working properly.